Actor, director, author, perfumer, activist: one can't help but gasp at the polysexual polymath known to us mere single/double tasking mortals as Alan Cumming. Today, the Scottish polymath is enjoying some downtime between his hit one-man reworking of Macbeth on Broadway – a marathon 72-performance run – and shooting season five of his hit TV show The Good Wife. We say downtime: we mean downtime Alan Cumming style.

"I've got a week off so I need to work on my memoir," says the 48-year-old, whose writing has appeared in The Wall Street Journal and Newsweek. "There's a lot to get through."

Too right. Alan Cumming doesn't really do weeks off. Between acting and directing, where other chaps might take in some sunshine in Ibiza, Cumming will record a solo album or stage a photography exhibition. He has worked for Kubrick on Eyes Wide Shut, gone up against James Bond in Goldeneye and strutted alongside the ladies of Spice World and Sex and the City. When he isn't writing his own projects or working as a contributing editor on Marie Claire magazine, he's authoring prefaces for the works of Nancy Mitford and Christopher Isherwood.

“I think everything I do is a variation of the same thing, which essentially is telling a story. I’m just trying to provoke, trying to get a reaction,” says Cumming.

And sleeping. Is that something he ever gets around to?

“I do relax,” he promises. “I just have a lot of things going on. I love focusing very intently on one thing and then switching that intensity to something else. I think it forces me to come to things fresh and with a new vigour. I can’t get bored. It’s just the way I roll, me.”

Between his many gigs – Brecht with Cyndi Lauper, Garfield with Bill Murray, Burlesque with Cher – Cumming campaigns for LGBT rights and assorted causes. To date, he has recorded a duet of Baby, It's Cold Outside with Liza Minnelli for Broadway Cares/Equity Fights Aids and the September 11 Fund and created the fragrance Second Cumming, with all proceeds from sales going to charity. Next year we can expect his book May the Foreskin Be With You: Why Circumcision Makes No Sense and What You Can Do About It.

“It’s mainly a medical book and it has taken a while because doctors don’t move very fast,” he explains. “Circumcision is an issue I’ve been involved with for a while. It’s just wrong. The idea that we’re inflicting this trauma on little boys and that it is justified for various social and cultural reasons is appalling. This is a crusade to open people’s eyes to that, to rethink it and also to consider the horrors that occur when it goes wrong.”

His film and television career has been varied enough to allow him alternate existences as a Smurf (he's currently playing in a multiplex near you as Gutsy in The Smurfs 2) and as Adolf Hitler (in Jackboots over Whitehall). Lately, however, the mega-hit legal series The Good Wife, has forced him to settle into a New York career groove. He currently divides his time between an apartment on Manhattan's Upper East Side and the upstate rural retreat he shares with Grant Shaffer, his husband since 2010.

"My brother came to visit and he took one look at the rolling hills and said 'You've bought your childhood'. It is very like the Scotland where I grew up."

Does The Good Wife – an Emmy-award winning vehicle for ER grande dame Juliana Margulies – take him away from all his other bits and pieces and his Scot-alike retreat?

“Not so much,” he says. “We shoot from late July until the end of March. But there are weeks when I’m only working one day. It’s a long commitment but I love the show and I actually like the dates because you’re in New York, at home, for nine months of the year. That gives me the freedom to do all my other weird little projects. I mean, I’m on call. So it’s like being an actor with the old studio system. Or a racehorse or something. A very, very pampered racehorse.”

Despite many irons in many fires, Cumming says that his role in the incoming weepie, Any Day Now, may be a career high. Set in the 1970s and based on a true story, director Travis Fine's award-winning custody drama charts the desperate efforts of an unlikely gay couple – flamboyant, angry Rudy (Cumming) and closeted district attorney Paul (Raising Hope's Garret Dillahunt) – as they seek to adopt an abandoned Down Syndrome teenager (Isaac Leyva, excellent). The film, an old-fashioned, devastating tearjerker – combines the clout of Kramer Vs Kramer, a speeding truck and a sock filled with oranges.

“I was blown away by it,” agrees its star. “It was such a compelling story. I just wanted to be a part of it. The script was different to the one we ended up shooting. But the bones of this great tragedy were already there. Then, by the time it came to making the film and Garret and Isaac and I met, we had formed this really intense relationship.”

Did he think of it as a campaigning film?

“I liked that it really jolted you out of complacency. And I loved that it was factually based. As a man who feels very strongly about equality I get annoyed that we’re supposed to be grateful for having the same rights as other people. The thing with this film is that even though it’s set 35 years ago, not that much has changed. The idea of two men adopting a child is still unusual and in most places illegal. So the reality of the situation was really important to me. Equality is something that should be important for everybody. That said, it’s not just about gay people wanting to adopt or about highlighting prejudice. It’s also a terrific story. And I’ve loved that people who have just chanced upon the film have responded to it emotionally and really loved it.”

A prolific talent who has featured in Shakespeare, the Spy Kids movies and everything in between, can he tell when a film is going to turn out as well as Any Day Now, I wonder.

“No way. It’s always a gamble. I really hoped this would work. But it has surpassed my wildest dreams and any expectations. The life it has had. The quality of it. The awards it has won. The response it gets from audiences. It has totally transcended its subject. It’s special. I’m so glad people are getting a chance to see it.”

Cumming was born and raised in Perthshire. He admits he had a difficult relationship with his forester father and the surrounding conservative environment. “It was very good for my imagination,” he says. “There was an oppressive force there with my father and that only encouraged my imagination more. My becoming an actor had a lot to do with that. The way I used to make up stories to amuse myself. I could blank out anything I didn’t want to think about.”

He may hold US citizenship but he retains both the accent and the sentiment of a Scotsman. “I feel Scottish,” he tells me. “I support independence. I understand more about myself and my Scottishness now than I did when I was living there.”

He has been married before, to Hilary Lyon, a fellow drama student at Glasgow's Royal Scottish Academy of Music and Drama, and has been romantically involved with the actress Saffron Burrows and theatre director Nick Philippou. The New York Times, quite understandably, once called Cumming: "a frolicky pansexual sex symbol for the new millennium." Is that a fair description?

“It’s a funny quote,” he says. “But I would never talk about myself that way. It’s just not how I think.”

In recent years he has settled into LGBT domesticity just as the entire LGBT scene has, in itself, settled into a kind of domesticity.

“There has been a huge change in LGBT culture because suddenly we have gay marriage,” notes Cumming. “And that changes the dynamics of the relationships and of the culture. The thing I love most about gay marriage is that now it’s part of gay culture. You can come together with a loved one and others can celebrate you. We never had that before. That’s a huge thing. It’s something that we can do in the open. And that’s not just good for gay society. That’s good for all society.”