If there is one thing that Rosie Boycott knows about her life, it's that 'stuff always happens'. She's right about this, of course. Her days have long been replete with drama and activity. Heroin addict, alcoholic, campaigning feminist, wife, mother, novelist, memoirist, newspaper editor, sometime star of Newsnight Review and Question Time; she has, done it all. Still, nothing prepares you for her latest incarnation.

Whatever else one thinks about Boycott - and opinions do, shall we say, divide - she has never struck me as a Mother Earth type, let alone a secret countrywoman. She has always seemed so deeply, unwaveringly urban: the kind of person who takes comfort in the sound of sirens and rattling lorries, who breathes in the morning stench of over-loaded dustbin and traffic pollution, and simply thinks: 'Yum! Another day, another dollar.' You can imagine all sorts of things hiding in the pockets of her Issey Miyake pleats (or whoever it is she likes to wear when in town): the telephone number of a cabinet minister, a stiff invitation to yet another literary prize, a spare Silk Cut. But a stray piece of straw? A seed potato? I don't think so.

Yet, here she is, at her Somerset smallholding - yes, her smallholding - communing with her pigs, eyeing up her turkeys, stroking the toasty, sun-warmed walls of her nursery garden. It's unnerving. The manner is the same as it always was: open, opinionated, perhaps a little brusque. But everything else is ... well, different. Sensible clothes, stout shoes (we'll come back to the shoes), no make-up. She doesn't mention the new Ian McEwan, or last night's Front Row on Radio 4, or even the latest outrageous bit of government spin (or not at first she doesn't).

Today, it's all livestock, fruit, vegetables and, especially, herbs. 'This is sorrel,' she says. 'And this is purple sage, parsley ...' We go into a poly-tunnel. 'This is all our salad. It's wonderful.' She nips a frilly leaf between finger and thumb, and chews on it ruminatively. 'Try it. The great thing about poly-tunnels is: no insects! You must take some home with you.' She fetches a plastic bag, and fills it with what the supermarkets like to call a 'medley' of leaves. She then gets an egg box and fills it with, obviously, eggs. Later, this lot does for my supper: a runny omelette with greens courtesy of Rosie Boycott. It's very delicious, but also - wouldn't you agree? - just a bit unlikely.

We go on with the tour. There are fruit trees and gooseberry bushes, potatoes and broad beans. There are geese and chickens and cute black piglets. In a potting shed, the radio is on. In a greenhouse, trays of lupins bask in the heat. It's an idyllic and dinky farm but not, as I had feared it might be, an ersatz Marie Antoinette-ish kind of a venture; there are no elaborate-looking bay trees in white planters, or pretty trugs laden with carefully cut flowers and Cath Kidston gardening gloves. There is dirt and mess and all the usual market-garden detritus (and smells). She marches on, brisk and businesslike, telling me about the tax man and the accounts as she goes. On our way back to her house across the field, we pass the geese again, and she announces that she sold rather fewer of them than expected pre-Easter, 'so that's 300 quid less than we were expecting this week'. She sighs. 'You know, maybe we will be beaten by commerce,' she says. 'But I hope not. Because if we can't make this work, being so protected and privileged, then really, what hope is there for anyone else?'

Boycott first pitched up in Dillington, which is near Ilminster, just outside Taunton, five years ago. She had come to visit friends, Ewan and Caroline Cameron (in the Nineties, when Boycott was editing the Daily Express, Ewan was in charge of the Countryside Agency). Boycott's husband, Charlie, had been full of enthusiasm for this trip; he grew up in a nearby village and, in spite of the cold weather that weekend, the two of them happily wandered Ewan's estate. The family stately home, Dillington Park, had long since been leased to the county council, and was now an adult education college (perhaps the most picturesque adult education college I have ever clapped eyes on). But there was, close by, another, equally lovely building, if far smaller: the Dairy House. That night, in bed, Charlie suggested that he and Boycott should think about one day becoming its tenants. She agreed; he was, she says now, simply voicing her own thoughts. Two days later, the phone rang at their home in Notting Hill. Were they still interested? Actually, yes. So, that month, they moved into the Ham stone house, whereupon they swiftly set about renovating its garden. The man who helped them do this - it was a big job and, besides, both of them had work to do in London; Charlie Howard is a QC, and Boycott, by this stage, was working as a freelance - was called David. The 'living willow house' and the sofas carved out of fallen oak trees that you can see there today are mostly down to him. And the pigs are his fault, too, in a way.

In the autumn of 2004, David asked Boycott and her husband if they would be interested in investing in a plant nursery, which he would manage. 'We looked at this nursery,' says Boycott. 'It was four miles away, and they wanted £90,000. It seemed like a lot of money - though we've spent more than that since - and 40 per cent of that was for the plants they'd failed to sell. But we'd got bitten with the idea of doing something.' In November, David came back to them with a new proposal: across the park from Dairy House, just north of Dillington House, was a Victorian walled garden, almost two acres and unused since the Sixties. This seemed a more realistic prospect, especially when Ewan agreed to extend a long lease on the garden and the surrounding five acres for a nominal £1 a year (the low rent was to compensate for the amount of work the plot required; mostly, what was growing there was old fridges).

So, in January 2005, the clearing began in earnest. David, with help, did the major work, but the idea was always that Rosie and Charlie would be a part of the business: sowing seeds, pruning fruit trees, selling produce at local farmers' markets. Every square inch was intended to generate income. Boycott's great dream - and she clings to it still - was that her smallholding would supply all the fruit and veg that Dillington House required. Each would sustain the other. And if this worked, couldn't it be a blueprint for the future? Couldn't hospitals and schools everywhere support similar ventures?

Of course, it wasn't quite as easy as that, and Boycott has now written a book, Our Farm, which tells the story of her smallholding, and the desperate struggle to make it pay so far, and can be roughly summed up as TV's The Good Life meets Richard Benson's The Farm, with a few campaigning top notes à la Fast Food Nation or Tescopoly thrown in for good measure. Among other things, it describes her effort to breed and sell pigs (the first batch proved too pathetically weedy to pass muster with top chef - he's a mate of Charlie's - Rowley Leigh, or the local butcher); to run a successful stall at a farmer's market (her herbs just didn't cut it alongside rival stallholders); and to set up an 'honesty table' in the porch at Dillington House (oddly, this does very well; the lupins and sorrel disappear rapidly, and are always substituted, somewhat miraculously, with cash in the tin). And all this is set against the backdrop of the battle, in Ilminster, to prevent Tesco from moving in and ruining another high street.

It's an easy book to laugh at - there's one moment when Boycott is out on the farm and actually admits to wearing a pashmina! - but, then again, it's not as though its author ever pretends that she and Charlie are dependent on the smallholding for their income. 'I expect there'll be people who say: rich bitch ... rich idiot,' she says, once we're back in Dairy House. 'I don't know how many times I can say it. We're lucky. We're privileged. That said, this matters a lot. It matters because of the big picture.'

Boycott sees herself as part of a movement. 'There's a cultural shift going on. We all have too much stuff. It makes me feel yucky. A lot of people are starting to feel: this wasn't what I signed up to as a human being. I want to be a part of that.' Last time she went to the supermarket - naughty! - there was a two-for-one offer on hot cross buns. 'Why do I need eight? Four ended up in the dogs.' She is disgusted with the peculiarly British mentality that loves dogs and even foxes, but shuts pigs and hens away, no room even to turn their heads. She longs for a return to the local.

'The government w***s on about communities and yet it has done everything, short of taking bulldozers through people's houses, to destroy them. We have one local abattoir left. When we tried to book our pigs in, there was a six-week waiting list. That's harder than getting into the Ivy if they don't know you.' Crikey. Still, I'm glad the Ivy has made an appearance. Perhaps the old Boycott is still in there somewhere, after all. Her mobile rings. And, yes, I'm relieved to see that she just can't help herself: sensible clothes or no, she has to pick up.

There is, of course, a back story to all this. For one thing, the farm came at a time when Boycott desperately needed a new project. The Express, which she had been attempting to turn into a left-leaning version of the Daily Mail, was sold to Richard Desmond and, at the beginning of 2001, Boycott found herself, for the first time in many years, out of a job (she refused to sack the more than 100 people he wanted to lose). At the time, she made light of this change in her life, writing a piece for Vogue in which she extolled the virtues of freelancing; it was even rumoured that she had started making cushions. 'Oh, I made it sound better than it was, is the truth,' she says, now, smoking merrily. 'My breath was taken away by how I fell apart. I thought I would be fine, but I was completely sideswiped by how denuded I felt.' She needed a new project. 'I love new things. It's the journalist in me. I needed a new venture. I can see, now, looking back, how much I wanted something.' I suspect that she had it in mind, fairly early on, to write a book about the farm. But it did not, however, fill the gap in her life straight away. Having been sober for two decades, she started drinking again. She and Charlie had had the farm for just a year when she had a terrible car accident; she was over the limit, and the whole thing was her fault.

The accident was extremely serious. Her leg was mashed up and, for a long period, it was thought that she might lose it. Why did she start drinking again? Wasn't the farm enough of a balm? 'On a newspaper, your rhythm is bang, bang, bang, and trying to change that was hard. I didn't have any sense of who I was. I didn't know who my friends were. I lost a lot of friends. A large part of my world just disappeared.' Did these people only want to know her when they thought she was powerful? 'Yes. That happens.' But even after the accident, the drinking didn't stop. She had at least three serious binges in the following 12 months. 'Mentally, I was thinking every day: shall I get drunk? My leg was a nightmare. Wondering all the time if it would be chopped off, and how I would cope with that. It was really frightening. Terrifying. I used to sit here and weep for hours, and get very sorry for myself. Charlie was very good, but it was tough for him. You become selfish as an invalid. Your world contracts. You become incredibly introverted.' Finally, she went into rehab. 'It [the accident] brought me into AA. I did 20 years of sobriety without AA, but now I kind of question whether I really was sober. Because I was a complete and utter effing workaholic. I didn't have any sense of myself outside my job.'

Although Boycott didn't lose her leg, she will always limp and, having lost an inch of it, has to wear a built-up shoe. But she doesn't resent this, perhaps because she is amazed to be here at all. 'People die in spades from this illness. I could have been bumped off in the car. It would have been very simple. But I wasn't, so I'm obliged to live, and if you're going to live, you should do it fully.' The farm is all part of this living fully. 'Being here was restorative. Planting things, seeing that they took a long time to grow. A lot of things that I've always thought - hippy, female things - have come together here. There's something people don't like about their lives now. Their possessions don't work for them. I don't get a kick out of it any more - materialism. But I do get a kick out of a piglet, out of stewardship rather than ownership. A lot of people said to me when I was down in the dumps: 'You don't need to do anything any more; you've been on Question Time, you've edited three newspapers. But you always need more. So I got this, and then I wanted to write a book about it. That's another reason why we have to succeed.' She compares Our Farm, rather deftly, to the memoir she wrote - long before everyone else got into literary confession - about her alcoholism, A Nice Girl Like Me. 'I thought: "I've put it out there that I'm an alcoholic, so now I can never drink again".' She hopes to pull off the same trick with Our Farm, only this time her aim is global not personal. 'It's a "fuck you" to Tesco,' she says.

Do I believe in her conversion to all things green? To pigs that can roll in the mud, and chickens with feathers so sheeny they look like crazy moving boas? Sort of. It will be interesting to come back in 10 years, and see if the fire still burns then. The trouble is, for all her passion and enthusiasm, she is easily distracted. She still, after all these years, finds it hard to say no to work (she and Charlie often make the long drive to Somerset in the small hours of Saturday morning, after Newsnight Review). And she is one of those people whose talk, however fierce, is often contradictory. In her book, she mentions several times how much she regrets the fact that she spent so little time with her only daughter, Daisy, while she was growing up (Daisy's father was her first husband, the journalist David Leitch, another serious drinker). So if she had her time over again, would she do things differently? 'Er, I'd like to say that I maybe wouldn't have worked on Wednesday afternoons,' she says. She pauses, and then laughs. 'Really!' But then she adds: 'Life would have been a nightmare without working.'

She is one of those people who likes to squeeze every drop out of life, and it doesn't take a shrink to see why. For one thing, in 1973, she headed east with her then boyfriend, John Steinbeck Jnr, the son of the novelist, and became a heroin addict, a habit that was only cured by a three-month stay in a Thai jail for dope smuggling. Though she went on to fall for the booze, too, this must have given her a sharp sense of time wasted. For another, she grew up with a mother who was thwarted and careerless. 'She was so unhappy. One of the most sad things I've realised since she died in 1980 is that she was really happy when she was dying. She'd had enough, she was glad to be going, and that's awful. I don't want to be there. She was absolutely nobbled by life. She was a huge motivator, in a completely negative way.' When Boycott co-founded Spare Rib in the early Seventies, she and her co-workers liked to say that they were women 'leading lives without maps'. 'I was greedy for life, and for experience,' she says. 'There's a lot to be done.'

She also has what she calls 'shaky' self-esteem. She tells me that her own education was 'crap', even though, as everyone knows, she went to the rather good Cheltenham Ladies' College. She also grills me about what I thought of her book, which is just not what you're supposed to do. When I ask her about Charlie, she says: 'He's a good man, and he's a nice man, and he's much nicer that any other man I've had. If you have an inherently low sense of self-esteem - you know, deep down I'm a piece of shit - then you attract men who treat you like a piece of shit. [I was just lucky that] I met Charlie at a good point, when I was editing the Independent on Sunday, and I was on top of it all, and it was going OK.' This is the only thing about her life that she would change if she had a magic wand; she would never have left the Sunday paper to go and edit the daily, where her tenure proved to be somewhat painful. 'But I didn't have a choice. If you say you don't want the next job you're just a wussy girl who can only cope with editing some pseudo magazine that appears on a Sunday.'

She and Charlie were friends when they were teenagers, and married a decade ago after being re-introduced by their mutual friend, George Carman (Charlie has children of his own; Boycott would have liked them to have a baby together but, at 46, it didn't happen). The symmetry of this pleases her. 'It's a kind of trust. If you got on at 14, and you're still getting on at 50, that's not bad. He's cleverer, and more considered than me. He's always having to rescue me. He's good at that. But the truth is, had I gone on drinking, I wouldn't be married now. I was very drunk. It's hard now to remember it. It's not that I'm trying not to tell you about it; it's just hard to go back to that place in my head. Some therapists say that if you know you're an alcoholic, and you decide to have a drink, that's because drinking is preferable to whatever it is you're running away from ...' What was she running away from? Loss, I guess. As she says herself, a good day on a newspaper is golden. And which of them is most keen on all this? 'He's more obsessed about being in the country. He's the one who moves primroses about. He likes the pigs, but I really love the pigs.'

Ah, the pigs. What was supposed to be a few vegetables, plus the odd hardy perennial, led, as these things do, to a menagerie. 'Yes, there are a huge number of baby substitutes here,' she says (I think she's joking). 'You do need a project when you are married.' Well, this is some project. When Our Farm ends, the Dillington nursery is turning a meagre monthly profit of just £382.47. They are selling less to Dillington House than they expected, and as she writes her final words not a single vegetable box has left the property. Her rare breeds of hens have failed completely, and they're behind on their pig schedule. On the plus side, the eggs and garden plants are going great guns. And the honesty table! It's turning more than £100 a month. Somerset people are very honest. I hope things improve, if only for the sake of David, a single father, and all the others the nursery employs. As for Boycott, it wouldn't surprise me if this was the start of another career entirely. I can see her on the stump, or running some green pressure group. Whatever she might say about watching things grow, the rhythm of her life is, and always will be, bang, bang, bang, not putter, putter, putter.

· To order Rosie Boycott's Our Farm: a Year in the Life of a Smallholding (Bloomsbury) for £14.99 with free UK p&p go to observer.co.uk/bookshop or call 0870 836 0885