In an interview with Digital Spy, Steven Moffat has revealed that the Doctor's search for Gallifrey "might take him a while".
Why did you decide to bring back Gallifrey?
"It was about a year ago, I remember thinking, 'What occasion in the Doctor's life is the most important?' - well, it's the day he blew up Gallifrey. Then I tried to imagine what writing that scene would be like and I thought, 'There's kids on Gallifrey and he's going to push the button? He wouldn't!' I don't care what's at stake, he's not going to do it. So that was the story - of course he never did that, he couldn't. He's the Doctor - he's the man who doesn't do that. He's defined by the fact that he doesn't do that, whatever the cost, he will find another way. So it had to be the story of what really happened, that he's forgotten. Of course he didn't - he's the Doctor ! He doesn't do things like that!
How will the search for Gallifrey figure into future Doctor Who?
"The Doctor has the possibility of going home – he can find Gallifrey – but it might take him a while, who knows? And who knows what he’ll do when he gets there? Get bored and run away again, I would think! But he has a mission statement."
"It was fascinating when Doctor Who first came back that he was this war survivor dealing with guilt and rage – that was his story. Of course, he slowly gets over that and then there’s a danger that he just becomes about… farting about a bit, which starts to take some of the baseline out of the show somehow. So we’ve given him something to pitch for."
He also hinted at how the new story arc will develop: "It’s not like we’ll spend every episode saying, ‘I nearly found it!’ – we absolutely will not do that – but it gives him somewhere to go. The Doctor doesn’t know he’s a character in a television show – he doesn’t know he’s having adventures for our entertainment – he’s got to have something to do and that will be the thing he does."
Series 35 begins filming in January 2014 and is expected to start airing on BBC One in the Autumn of 2014.