i live in Nottinghamshire and the city is great, theres plenty to do here thats not club orientated. That said, no matter what uni you go to theres always going to be people who not up for the party scene all the time, so you will find your own people. There is a train that does Nottingham to St Pancras so you will always have that link to London. The homesickness is totally natural, and the worry of student debt it going to happen at any uni.
I think if its making you feel that depressed, then take a gap year and re apply next year once you have your results. Maybe even try the london unis again in next years application.