Dad was a retired chemist who, in his 60s, fathered and fed me and my two sisters while Mum worked as a secretary. He made us curries, Chinese meals and strange concoctions. He was often unsuccessful. We would tell him, "It doesn't quite taste right", which, since he died, I've felt terrible about.

We had mint growing in the garden and the one job me or one of my sisters had when Dad cooked lamb was to make mint sauce. And I remember one lunch, getting quite stroppy, wanting to know who'd made the sauce that day. "I want to know!" I demanded. My mother said, "Put your head down" and then she poured the entire mint sauce over my head. I sat there watching it drip on to the plate.

At seven I was very unwell with glandular fever and put in an isolation ward, unable to eat because the pain of swallowing was so intense. But Dad would bring in a pot of warm, liquidised coq au vin hidden in a bag. He was never able to show affection emotionally or physically, but through food he did a comparable thing.

In theatre, there's no time for a proper meal. I used to eat at 10.30pm, but now, having children, as soon as I'm offstage I have to think about being on a countdown to being unconscious quite soon, to doing the school run in the morning. I think one needs to be more disciplined about feeding oneself, or one might just collapse and die.

I don't follow recipes. I'll read a recipe but then decide, "Well, it's sort of like this, then." Or I'll go to the fridge and think, I'll see what I can put together and I'll combine beetroot and sausage and prawns with goat's cheese sprinkled on top and think, "I like that they're all slightly pink. It looks fine and… actually, it is fine."

I loved chunks of crusty white bloomer dipped in Heinz vinegary salad cream as a child – that was the secret thing I'd sneak alone into the kitchen for. And even now I'll do that secretly and won't share with anyone.

What I like is eating when I'm not supposed to. If someone says, "It's lunchtime" I'm really not interested, but I'm interested in eating a bready, cakey, carbohydrate-based tea in the afternoon, or elevenses. But for breakfast I mix exactly the same thing every single morning without fail – Alpen Blue, Country Crisp Real Strawberry, Bran Flakes and a banana.

When Mum, quite a stickler, would tell us, "Don't hold your spoon so close to the bowl", I'd think "How can I not get close to the bowl?". Nowadays I require good table manners from my own three children, but they ask "Why?" and I say to them, poor things, "Because it looks better, it's better for you, and I say so". (Sitting at the table is a social act and I think has to be learnt. Perhaps that's why one has a spoon – to hit them under the table when they're using phones under the table. If we don't lose our rags sometimes, it gives children an incomplete vision of the complications and frustrations of family life and feeding. )

I've long thought that for my last meal on earth I will be perfectly happy with a granary loaf toastie with melted crunchy peanut butter and banana.

Tamsin Greig is in Jumpy at the Duke of York's Theatre, London WC2 from 16 August to 3 November; jumpytheplay.com