The whiff of autobiography - Planer freely admits that he has yet to live down his pigeon-holing in the public's mind as Neil the Hippy in The Young Ones - gets stronger when Neil James even borrows Planer's title for his novel. And the milieu of The Right Man - the real fictional Right Man this is, not the fictional fictional one - is surely a give-away. It is set in the world of actors and television.
The autumn publishing schedules are packed with stars of stage and screen reworking their daily lives into what Sebastian Faulks has recently dismissed as, "these things that pass for novels". His gripe is, presumably, that the plots of books like Richard E Grant's By Design, Eric Idle's The Road to Mars and Alan Titchmarsh's Mr MacGregor, are a cross between autobiography and wish fulfilment. So Titchmarsh's hero is a gardening show presenter who is also a national pin-up and Grant's romp is peopled by movie stars and set in Hollywood.
Planer has heard the unflattering comparisons. The Right Man may well, he acknowledges, be dismissed as another celebrity novel by a fading star with too much time on his hands. He shrugs and lights another roll-up. His mouth, already down-turned, giving his face its trademark hang-dog expression, purses. "I hope mine won't be seen as simply another comic novel. It comes out as more like an appeal than a statement. I mean, it's a pretty bleak story, don't you think? It's funny on the way, of course - I read it out loud and there were some funny bits."
It conjures up an odd picture of Planer, tall, hairline slightly receding, striding round the Thames houseboat that is his home, reading his own book out loud to himself. In some of the current crop of actor-writers, you might put it down to arrogance, getting off on their own prose. But with Planer, there's an element of lack of confidence too. The novel has gone through several last minute redrafts, and we spend 10 minutes working out which version of the story I have read.
Such concern gives a clue that he takes his writing seriously. But then, he's an actor, and perhaps he's playing up his role as an author, just as his small-screen creation, Nicholas Craig, became the consummate thespian in I, An Actor. Yet there are reasons for rejecting the stereotype of the bored celeb, filling his coffers with a variation on the theme of his personal diary.
For a start, Planer's acting career is going very nicely. He has just finished a well-received spell in the West End in the musical Chicago, and had returned to London on the morning we met, from filming The Grimleys, a new Channel 4 series, set in Birmingham in the mid Seventies.
Then, there is his already quite presentable bibliography. His account of the "true confusions of fatherhood", A Good Enough Dad, was a best- seller. He then penned a humorous how-to guide on therapy and divorce, and has published a collection of poetry and a short story.
One of the classic giveaways of the dilettante novelist, the moonlighting actors and comedians, is their total ignorance of literature. Since penning a book is for them little more than writing a long fan letter, they don't feel the need to learn from past masters and contemporary exponents of the craft. If pushed, a couple of episodes of Inspector Morse, and a week's worth of The Bill, is enough to grasp the vitals of settings and plot.
Planer, by contrast, turns out to be something of a bookworm, J G Ballard, Malcolm Bradbury, Peter Ackroyd, and even the medieval mystic Margery Kempe, all float into the conversation. He haunts second-hand bookshops. Writing, he admits, has become an obsession. "The most truly autobiographical element in my novel comes because I can't make a division between what I'm writing about and what my obsessions are."
His current obsession is the fate of dads. Indeed, Planer is in danger of becoming the patron saint of well-meaning fathers. That certainly was the effect of A Good Enough Dad, and led to him receiving requests from women wanting to know how they could make their partners nicer and cuddlier. Then came his own divorce and so, with The Right Man, he adds wronged dads to his portfolio.
Guy Mullin, Neil James's agent, and the central character of the novel, has tried to do the right thing by his wife and daughter, and indeed by his female colleagues. But one by one, they desert him. His wife runs off with a divorce lawyer. His business partner leaves him bankrupt, and even the aspiring actress who gives Mullin "a merry fuck" is only interested in what stage work her act of largess will yield.
While The Right Man is set in Planer's professional world, what is intriguing is how far it parallels his private world. Has he fallen into the trap of most first-time novelists - of writing about his own anguish?
"There is an overlap between me and Guy, but I'm not in the situation he's in. I have, comparatively, a successful separation. My son lives with me a third of the year. I don't have Guy's problems, but I have those fears. I realise how unimportant fathers are before the law."
This potentially puts The Right Man into a different league from the Richard E Grants and Alan Titchmarshes. Ben Elton, for instance, has won plaudits for novels like Popcorn, which tackle social issues, like the origins of violence.
If Planer's novel becomes a cause celebre for sidelined dads, part of a male backlash, then he could just have a second career on his hands as a writer - and even a third as a spokesman for an all-male constituency. He has, he admits, been to men's groups, men's weekends, and even a Families Need Fathers meeting. And, in keeping with the generally ironic tone of The Right Man, it would give the lie to Guy Mullin's confident prediction that television comedians can only fail grandly when they wander into the field of fiction.
`The Right Man' is published by Hutchinson on 1 October