Wouldn't it be too early to assume that London is superior to the other cities in every aspect? I'm pretty sure Norwich has its own charisma that the capital, perhaps, severely lack; take austerity and peace of mind for an example. The tutoring in both campus abide to the same curriculum, so I wouldn't say you stress too much on it. Plus, although you may wake up to a lovely morning in the city of mist, strolling along Oxford street with a cup of Earl Grey in your hand (that's a real stretch, mind you, it's more likely you'll be squeezing through a solid mass of people trying to get onto a tube), you'd definitely miss out chasing a bunch of bunnies along a vast lake and an outdoor picnic. The music school in Norwich is fantastic, it's located in the heart of the campus where you could look out a window and see a forest and a green plain, then look out another window to students strolling idly along The Street. Sometimes you'll get a bunch of people flocking around your window asking for an encore, and isn't that just great?
London may be a big city where every material goods are just an arm's reach away (I'm not going to deny that it's one of the most beautiful place in the world) but trust me, in Norwich you'd find more ease, relaxation, and amongst the crowd genuine vitality.