Hasn't the Oxbridge deadline already passed? I thought it was the 15th Oct if you want to apply for 2011.
Anyway, I picked five choices for physics, just got to wait for my tutor's reference to all be done and sent off. I'm applying to UCL, Nottingham, Exeter, Portsmouth, and Sheffield. UCL/Nottingham are the ones I would ideally want to go to.
ucl and nottingham are both great choices uni-wise for physics, just know that even for first-years the former's accommodation is pretty fucking expensive (even worse than imperial). you get a bigger loan to cover it but that means you'll be in a lot more debt afterwards of course. have you been to visit any of the unis yet?