You're still asking about music. As I explained on your other thread, you almost certainly haven't got a moggie in Hades chance of being accepted onto a music course without a Grade 8 performance qualification.
As to whether you should choose Manchester Met or Chester (or, indeed, any other uni open to you), you need to look beyond the course itself and look at websites which tell you what student life is like in those cities. You're going to be there for at least three years, which is a big chunk out of your life, so you need to ensure that the experience as a whole will be FUN. For example, look at the accommodation options at each university. If you'd have to live in student accommodation which is miles away from the main campus and/or, even worse, miles away from the city's nightlife, you could end up feeling trapped and bored. Choose a uni where you'll be at the very heart of everything that's going on.