We love Big Bang Theory. It's not science fiction, but it's an ace comedy show about super-intelligent geeks with limited social interaction skills. Sound like anyone you know? There's no end of science fiction related debates (one episode started with the line 'You know what the problem is with teleportation?') and howl can you not like a show that has a bunch of guys show up at a Planet of the Apes movie marathon to find the whole audience wearing monkey masks?
Most importantly, it's really funny.
It's on Channel 4 and E4 and well worth searching out.