Happy New Year!
Now, unlike my last post of last year, there isn't a Being Human game on the way... as far as I know... and I did ask Angus about it...
But anyway, it's a more well represented area in gaming-land anyway, with the second-biggest RPG around being Vampire. I'd probably go with something a bit lighter for a game where there's just the one vampire PC, to follow the show's example. Not much need to differentiate, and not many superhuman powers on display. Pretender maybe, since it doesn't put much emphasis at all on the action side of the genre.
You'd need to think about how the setting works - unassuming vampires, outcast werewolves, an afterlife like an immigration centre where it would be easy to show too much.
And of course, get in now before the American version. Doy.