I go to a top ten red-brick university. A friend of mine is top of the year in her subject, and some of her essays are so good that they have to be sent away to externals just to check that the supervisor isn't going mad. She's got a place to do a taught masters at Cambridge next year, but in the mean time she's had a fantastic time here, on an excellent course, with lots of time to have a great social life and get involved with lots of extra-curricular things.
I suggest you take a step back and look at some of the things you could potentially do at Warwick which you might not have time for at Oxford. Go and do conservation work in Africa for three months in the summer, or run a marathon, or audition for a show, or set up your own society, or whatever takes your fancy. Really throw yourself into university life, whilst at the same time working really hard for your degree. Warwick may be in the middle of nowhere, but you can get involved in lots of extra-curricular things which will take you away from Warwick, to other parts of the country or even abroad, on a regular basis. I can see how it might be a little easier to get bored on a campus like Warwick, but I'm sure you can find really amazing things to do and have a fantastic time if you really want to.
If you're as good as you say you are, get involved in lots of really exciting opportunities, AND get a first. Then apply for a masters at Oxford or Cambridge if you still want to.