Heston Blumenthal has always enjoyed grandiose gestures but even by his standards the moment when he gets out his own giant coat of arms is full on. “I commissioned this from Dave McKean who illustrated The Fat Duck Cookbook,” he says, lifting it on to the table of the boardroom, located in a building overlooking the three-Michelin-star restaurant he opened in Bray, Berkshire, 20 years ago. “The real one is rolled up in a box somewhere.” Apparently you need an OBE and a degree to be offered one of these by the College of Arms. Blumenthal got his OBE in 2006 and has a bunch of letters after his name, albeit honorary ones, given he left school at 18. “It’s probably one of the things I’m proudest of,” he says gazing at it. “Coats of arms were designed to tell a story.” Right now, he says, story is what he’s all about.

He takes me through the imagery. “The helmet down signifies the OBE. There has to be an animal so it’s a duck, a golden duck because that restaurant is my golden egg. That restaurant has shaped me more than any human being.” We work our way down, past the golden apple, signifying taste, and the outstretched hands, signifying touch. But the most significant part, given Blumenthal’s latest project, is the two words at the bottom. They read: “question everything”.

Blumenthal has been questioning everything for a while now. Last year he announced that from February 2015 the Fat Duck would relocate to a hotel and casino complex in Melbourne while the mothership underwent a £2.5m renovation. “The move to Australia was a great opportunity to question what the Fat Duck is. In the sense that we cook food and it’s served to people, we’re a restaurant. But that’s not much, is it? The fact is the Fat Duck is about storytelling. I wanted to think about the whole approach of what we do in those terms.” Behold: the chef is no longer cooking your tea. When the Fat Duck re-opens at the end of September, he says, they will be in the business of telling you a tale.

Described like this, it makes the chef sound questioning but focused. In truth he’s benefiting from editing. A conversation with Blumenthal is fast, furious, scattergun and sometimes frustrating. He leaps off down intellectual tributaries and digressions without warning, with a shout of “This is important!” It has been this way over the 15 or so years that I have been interviewing him; a chaotic, exhilarating ride through the mind of a restless man. We are meant to talk for 90 minutes but it stretches to over three hours and even then we need a follow-up phone chat. He mentions chimp brains and space food, multi-sensory approaches and his habit of being a “pleaser”, which he is trying to discard. He talks so much about this stuff, I ask him whether he has been in therapy. He has the language of a man who has paid hard cash to talk about himself. He grins. “Of course I have,” he says. “Therapy is great.”

There must be a lot to talk about: not just the end of his marriage of more than 20 years back in 2011, or his spell as fodder for tabloid gossip, but the whole knotty business of being Heston Blumenthal, the mad professor of the kitchen, as he approaches 50. After a golden period when TV programmes including Feast and In Search of Perfection were praised to the stars for engaging new, often male audiences in cookery shows, others came in for criticism for being contrived.

“I do think the TV work was becoming a bit formulaic,” Blumenthal says. “But the underlying work on the food was always robust. Even when we were making the giant foods they were edible and tasted good.” The problem, he says, was the “linear” approach of television programme making, where the end result is already known. “I understand why TV has to do it because it all costs a lot of money. But in the end you’d be shooting the intro and outro at the same time and that can’t be good.”

Still, he says, there can be moments of authenticity on television. He’s currently working on a show about revolutionising astronaut food. He has undertaken basic space training, including experiencing zero gravity in a plummeting plane, and is working to get the first cup of tea drunk in orbit by a British astronaut. “We were sending some samples up to the space station recently but the rocket exploded on takeoff. If you want TV jeopardy that’s the real thing.”

Back in Bray at his development kitchen, he and his team have been using the very non-television non-linear approach to work out what the Fat Duck should become. He publicly disowned the term “molecular gastronomy” years ago, preferring to describe his approach as modernism. “The Duck will still use multi-sensory techniques,” he says. I wonder out loud if he’s hunting for some ideal of the perfect restaurant. He denies it, despite having launched an outlet at Heathrow Terminal 2 called the Perfectionists’ Cafe.

“Perfection is the enemy of creativity. All these ideas of success and failure just equal fear of failure, judgment of others and blame of others. It restricts creativity. The opposite of failure is discovery. Failure is an opportunity to learn.”

That, he says, is what he’s trying to do right now with his much-loved restaurant. He may have his pubs, the Hinds Head and the Crown. He may have Dinner at London’s Mandarin Oriental (another is soon to occupy the site that housed the Duck in Melbourne). He may have his growing range of food products for Waitrose and his kitchen implements for Sage, but it all begins and ends with the former pub just across the road from us.

So, I say, is this a relaunch of the Fat Duck, the restaurant made famous by the delicious whimsy of egg and bacon ice cream, snail “porridge” and “Sounds of the Sea”, the shellfish eaten to a headphone soundtrack of crashing waves? “It’s a maturing of the Duck,” he says. The most annoying question he’s ever been asked, he says, is: “When will the menu change?” Many of the dish titles have indeed been on the multi-course tasting menu for years.

“The titles may stay the same,” he says, “But the dishes change.” That said, he admits that some have evolved as far as they can. So what happens to a Blumenthal dish that has stopped developing? “It comes off the menu. We may put them into a hall of fame, available for people who have come from the other side of the world for them.” Among those coming off are the orange and beetroot jellies – the orange is golden beetroot, the red, blood orange, which screws with your head – the egg and bacon ice cream, the mustard ice cream with red cabbage gazpacho, the snail porridge, the quail jelly and the salmon with liquorice.

What about “Sounds of the Sea”? He’s almost affronted. “No, that stays,” he says, along with the savoury ice lollies made to look like Twisters, Fabs and Zooms. Thinking about the idea of a meal as a story he turned for help to Lee Hall, writer of Billy Elliot. “He looked at the menu and said that with the ice lollies and the Sounds of the Sea this is basically a holiday. It’s about those childhood feelings of adventure, discovery and curiosity.” What does this mean for diners? “It means the menu will now be a story. It will have an introduction and a number of chapters and the chapter headings that will give you an idea of what is coming.” I ask him for details and he references Alice in Wonderland but then says only: “It will start with breakfast.”

As contrived as all this sounds from the outside, this is Blumenthal being consistent with things he has said in the past. When he put breakfast cereal made of dried parsnips on the menu back around 2002, he said it was because the flavour of the milk they had been soaked in reminded him of the end of a bowl of cornflakes from when he was a kid. The sardine on toast sorbet was a way of reflecting the flavours of a Sunday evening supper from childhood back at you.

He is fascinated by nostalgia for childhood and has long used the phrase “like a kid in a sweetshop” to describe how he wants his guests to feel. Now, he says, he has finally built his sweetshop, at a cost of more than £150,000. “It’s an automaton, in the shape of a doll’s house that will come round on a trolley at the end of the meal and puff smoke rings out the chimney as you choose your sweets.”

Those choices will be personalised, as he hopes other parts of the meal will be. Much has been made of high-end restaurants Googling their guests in advance. Blumenthal says they’ve been doing that at the Duck for years. Now they want to take it further, eliciting personal details from guests in advance, perhaps through whoever is hosting the table. “I called up Derren Brown and talked to him about how we could find out things about people without them being too aware.” As a result he is toying with using auto-suggestion techniques so that diners get what they think they most crave.

Right now, Blumenthal says, the story they’ll be serving is his, “from childhood holidays in Cornwall between the ages of five and seven. I’m using myself. I’m morphing into my food. My food is morphing into me.”

But in time, he says, it will become the story of his guests as they return to eat there again. This seems a little optimistic. The Duck only seats 40 per service and, given there are 30,000 requests a day, bagging a table just once can seem like a miracle, let alone managing to do so multiple times. To manage demand they are introducing an advance ticketing system of the sort first used by Alinea in Chicago. “There’s evidence that thinking about the bill to come at the end of the meal detracts from the experience so this gets it out of the way,” he says. You will only be able to book online. An element of lottery may be used, though he’s not sure. “Everything is in flux,” he says.

He knows the price will have to rise (the tasting menu cost £220 a head when the restaurant closed at the start of 2015). Does it frustrate him that it’s completely out of reach for so many? “Something can still be expensive but value for money.” In any case, he says, it’s not vastly profitable; he regards it as the thing from which everything else springs. “We don’t actively intend to lose money, but that’s not what it’s about.” He waves at the shelves of Blumenthal branded products just outside the boardroom: the Earl Grey and lemon gin, the caramel apple pie popcorn, the sauces and puddings and pies. “That’s what all that is about. We use the same techniques and care in those as in everything else so everyone can afford to taste what it is we’re doing here.”

The products aren’t just cashing in then? “Absolutely not. I treat all of those products with the same care. Every week we send someone out to buy all of them from Waitrose to check them.” He tells me he was recently offered a million pounds for two days’ work a year for three years, by a winery. “I said no because I didn’t like their style of sauvignon blanc. I’m going through an expensive divorce. If I was just about the money I would have taken it.”

Is he not at all concerned that this new approach to the Fat Duck will be dismissed by many as pretentious and arch; that he has completely over-thought what is just a plate of food?

“You can’t please everybody. If they say it’s just a bloody plate of food that’s their choice. I want to give pleasure to people but out of compassion and empathy rather than because I want them not to think less of me. That would be lying to myself.”

That said, he insists no dish will ever go on the menu unless it is a delicious plate of food.

An assistant announces our time is up, and that there is a meeting waiting for him downstairs, to which I am invited. Around the table are illustrator David McKean, now appointed “director of story”, and Mike Duckett, a “coaching psychologist” who has worked with Blumenthal for years, along with various chefs in their whites and a slightly startled looking expert in fonts, who is to communicate emotions through the type of print used on the menu.

Behind, on a board, pictures are pinned up. One side, holding pictures of Snail Porridge and the like, is marked “Hall of Fame”; the other, with 16 or so images, is simply called “The Story”. It includes a picture of a cereal variety pack, a tuile made to look like a log, and a cartoon of sheep leaping a fence. Gently, as everyone else takes notes, their boss outlines his ideas: he begins talking about diners disappearing down the rabbit hole like Alice; about the need to “open and close loops” across the meal, so that there is a satisfying narrative. He points at the cartoon of sheep. It represents a dish about going to sleep “so everything has to be soft rather than acidic”.

It feels like the script conference for a movie or a TV drama or a concept meeting for an extremely eccentric theme park. It does not feel like the meeting for a restaurant. Everyone is rapt. What matters in here is the story. Is everyone sitting comfortably? It seems they are.

Then Heston Blumenthal will begin.

The Fat Duck: a brief history

1995: The largely self-taught 29-year-old Heston buys a Grade II-listed pub in Bray, Berkshire, converting it into a restaurant serving bistro dishes. Main courses include salmon, puy lentils, pea and horseradish sauce; roast cod with braised cocoa beans; steak and chips with sauce Moelle.

1999: Awarded one Michelin star.

2000: Introduces a tasting menu, winning praise for unusual dishes such as crab risotto with crab ice cream. The Guardian’s Matthew Fort declares, “If, on paper, it seems poised on the edge of self-parody, these dishes resolve themselves brilliantly on the palate.”

2001: Awarded a second Michelin star.

2004: Awarded a third Michelin star. It saves the restaurant, which is only two days from bankruptcy.

2005: Voted No 1 in the World’s 50 Best Restaurants awards, ahead of Ferran Adrià’s el Bulli in Spain.

2006: Blumenthal is made an honorary doctor of science by the University of Reading.

2007: According to the Financial Times, the restaurant now has a turnover of £4m. Weekly wage bill is £35,000.

2008: Earns Good Food Guide’s maximum score.

2009: Closes temporarily after norovirus affects 240 diners. Contaminated oysters are the most likely culprit.

2012: After eight years in the top 10 of the World’s 50 Best list, the Fat Duck falls to No 13.

February 2015: Heston closes the Fat Duck, moving it to Melbourne for six months. Bookings are made via a ballot: 250,000 people enter.

Autumn 2015: Re-opens in Bray with new menu.

The Fat Duck will re-open in October; thefatduck.co.uk