The dating comedy, which also stars Sharon Horgan and Anthony Head, only began on Channel 4 last month, and Stephen revealed the cast are already hoping to make more.
Stephen said: "It's going well actually, Free Agents. We've had a great response and we're waiting to see if we'll get another series. So the big bouffant hair do hasn't put anyone off, and neither has Anthony Head's filth that comes out of his mouth - housewives' favourite Anthony Head and his potty mouth!"
The Green Wing star is currently appearing alongside Jessica Hynes and Andrea Corr is a revival on Alan Ayckbourne's Norman Conquests at The Old Vic, which is now going to Broadway.
Speaking at the Olivier awards, Stephen revealed he believes theatre will thrive in the credit crunch.
He said: "Yeah definitely because you go and something good it's brilliant. Like anything else, when you go and see a bad play or a bad film, it's a disappointment, but when it's good it's fantastic and people have been going to the theatre for 3,000 years so I don't think they're going to stop going now."
Sheridan Smith, who was presenting an award and attended the event at London's Grosvenor house with boyfriend James Corden, agreed.
She said: "It's theatre isn't it - it's the best form of entertainment I think. There's just been a new scheme launched to get people under 25 coming so we need to get more people coming to the theatre. Come down, it's great, you'll love it!"