It does. VERY huge. It even crosses over with other universes at some points, like the Marvel universe, for example.
And there are so many spin-offs from the main Doctor Who universe as well. You have the tv-show spin offs like Torchwood and Sarah-Jane and the K9 spin-offs, but then you have audio spin offs too, such as Gallifrey (what this RP is based off), Bernice Summerfield (oh which crosses over with Sherlock Holmes at one point, so yeah, apparently he's part of the Doctor who universe as well), Jago and Litefoot, A Romana spin-off with her adventures in E-Space...the list goes on.
I mean really, if you look past the TV show at all the other forms of media there are countless audio books, novels, comics, and now computer games as well. I honestly don't know how long it would take to go through them all, I don't dare think about it. I don't think I'll even touch things like the novels (although I've read a few based on the ninth/tenth doctors). Way too time-consuming.
And it's been around for almost 5 decades now, Quinny ;D The 50th Anniversary of Doctor Who is in 2013.