i study maths at UCL... i must say that im very happy with the way my course is structured and with the whole experience Ive had so far (im a 3rd year), a couple of my friends who chose UCL over imperial said they did because they felt UCL had a friendlier environment and it provides you with a lot more options.... being multi-faculty...i suppose warwick would be the same. I dont doubt that as a maths department imperial is probably better, and has got better research facilities etc...
Also i can guarantee that the staff here is fantastic, and really take an interest in you performing well...whether that means you wanting to change course, modules, need help etc... again this might be the same at ic and warwick.