Sara’s someone who’s managed to get to the age of 40 without really changing or challenging herself in any way whatsoever. She works hard and is very good at her job as a vet, but she hasn’t developed personally in any way.

She has a series of encounters, not really relationships because she’s too scared to let anyone get close to her. This is an increased source of frustration for all of her friends who feel she’s wasting her life by not being true to herself. Sara’s overriding story is to come to terms with who she is and to stop being so neurotic and ashamed of herself. This is all helped along by a truly unlicensed therapist played by Joanna Scanlan who hasn’t got a single qualification to her name but has bought many off the internet!

What were your reasons behind writing the show and how do you want people to view this comedy?

I wanted to write something that was very much an ensemble piece, where people are falling in love and being disappointed, where friendships are being tested and where a group of people are at a point in their lives where they need to make a decision. Where are they going in their relationships?

For example the whole Justine and Jamie thing, they’ve had feelings for one another for 20 years but have never done anything about it. Everyone’s coming to terms with something in this comedy.

More importantly than anything else, I wanted to write something from a little experience about being gay but firmly base it in the real world, which is predominantly heterosexual. It’s not a political piece – it’s just saying we’re all the same. I’d like people to look at Sara and feel sympathy and want her to get together with Shelley Conn’s character Eve and for them to feel sad when it’s complicated.

By making the gay character funny and sweet but above all normal, you make a far better, longer lasting statement than you would if you had an entirely gay comedy. Society has moved beyond that, most of my friends are straight, this is my final sigh of ‘come on, we’re beyond this now’ and being gay is maybe the 47th most interesting thing in my life. I want the whole process of ‘coming out’ to one day not be a big deal or a great fanfare and if this piece contributes to that, then brilliant.

Why did you write Sara as a vet?

I wanted to set Heading Out in a real world, a concept I originally struggled with as I don’t have a proper job. The office has already been done but I do visit the vets a lot with my lingering, sick, vomity pets so it got me thinking.

What’s great about a veterinary is that everyone goes there, posh people, poor people, people from every ethnicity, background, religion and they’ve all got animals that will eventually need to go to the vet. So it gave me a lot of scope as a writer to just plonk anything in there. In episode three you’ve got Mel Giedroyc’s character as a Russian guard’s wife, dripping in jewels and cash and in the same waiting room you’ve got a guy with a manky, old collie who just put his pipe out. So I really like that.

Did you have any nightmare scenarios filming with any of the animals?

The animals were, naturally, appalling. Brian who plays Smithson, Shelley Conn’s dog, barked every time he saw a sound boom which was every time. He’d try to lick the boom, he’d try to eat the boom, he’d try and have sex with the boom and that went on for hours and hours, and he was constantly trying to rear up and knock me off my feet! The Borzoi dog from episode four was so nervous that its back legs gave way the whole time, plus she was meant to be a boy – the whole point of the scene was that it was meant to be a dog that can’t get it up! Realistically, the only animals that behaved were the dead stuffed cat or the snake.

Do you see any of yourself in Sara at all?

I think the hesitancy, the shyness and the awkwardness I definitely see in myself. Thankfully I’m not as neurotic and I’m not a coward. I don’t have it in my personality to be frightened of things. The hardest thing about writing Sara was that I always knew she had to be likeable and I had to work quite hard at that. She’s also not the funniest person in the show and there were times where I thought ‘I wish I’d just written three scenes for myself, where I can walk on, be hilarious and then leave!’ But instead Sara needs to be the emotional heart of every scene and the job with her is not to be funny but for people to understand her situation because then that’s the base level upon which all of the other characters come to life. It’s such an amazing cast that at times I just sat with my mouth open and then suddenly realise, ‘Whoops! I’m meant to be acting’!

Speaking of the cast what was it like working with everyone else?

Justine is played by Nicola Walker who is one of my oldest friends.  I’ve known her since I was 18. I now have to deal with the fact that not only is she my friend but suddenly I have to act with her; I had to raise my game considerably because I’ve always been overwhelmed by her talent. I wrote the part of Justine with her in mind and after the first read-through she went back to her husband and said ‘I don’t know how to play this part’ and her husband said ‘It’s you, you just don’t know that Justine is exactly how you are!’.

But joking aside we could all say that about each of ourselves, there is a very sober and serious side but there’s also a side to Nicola, as there is with me, that’s very childish and we just laugh and play. I wrote her part out of love, except Nicola’s very clever and the Justine is more of a simpleton!

There are a lot of phallic symbols in Toria’s place of work, was that your idea?

That came from Joanna Scanlan actually. There’s a sense that Toria is a sexual libertine; Sara is so uptight and embarrassed about intimacy, so I wanted her to be confronted by someone who was the complete opposite. In Joanna’s head she’s playing a female version of the Marquis of Bath so she’s permanently on a sexual odyssey. So with that in mind when it came to designing her flat there was this sense we should have a lot of fertility symbols, which she will often use to illustrate certain crazed situations, much to Sara’s utter horror! For example Toria uses a metaphor of a plane crashing into a house and just grabs a penis statue and drives it into a stack of Jenga bricks.

What are you up to next?

I’ve started to think of some ideas for a drama, at the same time I’ve finished a radio four show called Dilemma that I host, and then The Great British Bake Off begins in April. It’s back and cake-ier than ever so that will occupy 10 weekends of my summer.

‘Heading Out‘ airs on BBC Two on 26 February at 10.00pm to 10.30pm