I think there is a very good Gracie Jujitsu school in Nottingham or Leeds. Not too far from you but not right next door either. It depends on whether you actually want to train MMA or if you want to be a boxer. There are millions of boxing schools.
i was looking around and muay thai looks the most interesting, ive never done and mma training befor played rugby for 7 years and descovered the world of mma and fell in love, my problem at the moment is i can not drive so getting to a gym will be difficult