Hi there,
I live in London. To be honest I would stay away from most of the big cities inless you have an income that allows for you to be based in the rich areas in the cities.

You will find the 'industrial' or former towns / cities are really bad. UK is dealing with a surge of teenage gangs at the moment and there are loads of areas which should be avoided. Let me know which parts you are looking for and I will tell you what I know.