David Baddiel is a comedian, TV presenter, screenwriter and author of novels for adults and children. His TV programmes have included The Mary Whitehouse Experience and Fantasy Football League with Frank Skinner. In 1996, Baddiel and Skinner co-wrote the lyrics to Three Lions, which returned to No 1 in the charts during this year’s World Cup. Last year Baddiel’s show, My Family: Not the Sitcom, was a sellout in the West End. His new novel for children, Head Kid, is out now.

You’ve written six children’s books in the past three years. What inspired you to throw so much energy into this new phase of your career?

I don’t really operate in terms of a career plan. At no point did I think “Oh, I’d like to be a children’s writer”, or “Look at what David Walliams has done, I’ll do that too”. The way it happened was, once I had kids I started making up a lot of stories for them and improvising stories with them. Then there was a very specific moment when we’d just been to Harry Potter world at Leavesden, and my son, Ezra, who was eight, said: “Dad, why doesn’t Harry Potter leave the Dursleys and go and find some better parents?” Well, the reason for that in literary terms, I think, is that JK Rowling wants to make Harry’s world as mundane and horrid as possible so that the world of Hogwarts is more magical by contrast. But I didn’t give him that answer. I said: “Well, that’s given me an idea”, and the idea was to create a world in which children can choose their own parents. And that became The Parent Agency, my first book for children.

Head Kid is about the naughtiest boy in the school swapping bodies with his ultra-strict headmaster. Did that idea come from one of your children too?

It came from a different kid: Enzo, who’s the son of Ann-Janine Murtagh, head of children’s books at my publisher, HarperCollins. She and I were talking and she said her son loved the way my books are all set in the same school – a not very good comprehensive called Bracket Wood – and thought it would be brilliant if there was a story about a naughty pupil and a very strict new headmaster going into battle with each other. That idea evolved into the body swap thing. So I have Enzo to thank for Head Kid.

How does being a comedian feed into your writing for children?

Being a comedian gives you licence to remain quite childish yourself. I think that means I have quite a good radar for what the child in me would think and say and feel in numerous different situations. I am actually of the belief that we are all at heart children – we’re all winging it with adulthood, pretending to be grown-up. Even as our bodies grow old and decay, inside we remain between the ages of about nine and 14, except for maybe Michael Gove.

Facebook Twitter Pinterest With Frank Skinner during the heady days of Euro 96. Photograph: Rex

The child in you evidently likes toilet humour as much as the next child, if Head Kid is anything to go on …

I find myself unable, when I write a children’s book, not to have at least a little bit of toilet stuff, because I know that children just find it immensely funny. There’s a scene in The Parent Agency where the main character meets some prospective parents and they tell him he can say or do whatever he likes. The first thing he does is just say “bum, poo, fart, wee” over and over again. I read that to kids when I visit schools and they go mad with laughter. I mean completely mad.

Do you find it easier to write for children than to write adult fiction?

That’s a difficult question, and I know children’s writers get very angry if you say that kids’ books are easier to write. One way in which they straightforwardly are is that they’re shorter. But I write children’s books attempting to make them as full and as rich and as funny as an adult book – and there are different challenges, actually. You have to find ways of describing complex feelings quite simply. And that can take quite a lot of time.

Was reading encouraged while you were growing up?

We lived in a slightly weird household, and one of the things my mum used to do, before she started collecting golf memorabilia, was to collect old children’s books that she would give to me and my brothers. So I grew up on Billy Bunter and Just William. I was obsessed with Billy Bunter. In fact, when I was 11, I was a member of the London Old Boys’ Book Club, which was a fan club for Billy Bunter, and everyone else in it was 70. So that was slightly foisted on me by my mum, but I did really love those books as well. We were a lower-middle-class family; my mum was a refugee from the Holocaust, and I think there was a sense in which the world, as pictured in Billy Bunter, was this very sort of crumpets-over-fires, turreted, fairytale world which I found very exotic and kind of romantic when I was growing up in Dollis Hill in 1975.

Do you still read a lot now? What books are on your bedside table?

At the moment I’m reading Hark by Sam Lipsyte. He’s really great. I had become slightly disenchanted with the literary novel. I used to read a lot of literary novels, particularly American ones. John Updike is my hero. I’ve read all of him and all of Roth, all of Bellow, all the Franzens and the David Foster Wallaces and all those people. And also lots of women: Carol Shields, Anne Tyler, Elizabeth Taylor. But I found myself falling out of love with the literary novel. Every time I read one it felt grandiose to me. Then I read a couple of Sam Lipsyte things and he’s changed that for me. He’s an unbelievably brilliant writer at the level of the sentence. I also read more nonfiction than I used to. I read a lot about quantum physics.

Facebook Twitter Pinterest David Baddiel on stage for his show My Family: Not the Sitcom in 2016. Photograph: Marc Brenner

Really?

That’s about my dad, I think. He was a scientist, had a PhD in chemistry, and was a very dominating figure. When I told him I was going to study English literature he described it as a waste of a brain. So I think my becoming interested in physics is a return to him in a way, or to whatever it was I turned my face against when I was 18. Now, I’m really fascinated by anything Carlo Rovelli writes. And I read Brian Cox’s books. The thing about quantum physics books is that I read them, for a second I think I’ve understood, and then it closes again. I’ve written a play about this, called God’s Dice, which I hope is going to be on at the Soho theatre next spring.

What’s the play about?

Quantum physics and religion. It’s about the interplay between them, because I think that if you start to understand quantum physics you get a sense of the miraculous. And it almost takes a leap of faith to believe that what the physics is telling you is true, that the world is actually like this. You feel it can’t possibly be the case that, for example, if an electron is spinning in one direction, another electron that is entangled with it will be spinning in the opposite direction 2,000 light-years away.

So is theatre a new passion for you, after My Family: Not the Sitcom?

I love theatre, but at the end of the day it comes back to the same thing, which is I got an idea that there was something religious about quantum physics. And when I have an idea, I want to write a story about it, whether it’s a West End play or a kids’ book. It’s as simple as that, really.

• Head Kid by David Baddiel is published by Harper Collins (£12.99). To order a copy for £11.43 go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99