Indeed London is much more expensive. I left the city for that reason myself, but probably for a year or two career wise it might be great. Long term, I fully agree with you re nicer apartment and more cash.
I'd second that: work in a large company or a startup (if that interests you) in London for a couple of years to learn the ropes and build your career.
Then the world (or the North East) is your oyster. Or course, it's always difficult to move once you've settled down, even in London.