I might do, I'm still undecided which is a bit annoying. I think it depends on my grades more than anything!
Cepb, I don't think it does at all, however that is of course if you do worthwhile things in the year, and use your time wisely. If you do, universities will consider you and might even favour you if you've done lots of interesting things!
For me, I'm undecided mainly because I wouldn't know where to start with a gap year. I would travel, but I don't feel up to it to be honest, and I just want to go straight to university!
But again, I won't speak too soon... it depends on how I do next year.