I'm also interested to know why live in Harrogate to work in Leeds - I assume there's a practical reason? If you don't want to live in Leeds and were going to commute by train anyway, you could live in York - more going on than H'gate, less blue-rinsey, prettier (to my mind), and on the mainline..
As for whether you can leave London for parts north, I don't really understand the idea that you can't live away from a place, I guess I've never been so attached to one city. I mean, I'm planning to stay in York, but if circumstances (job, love etc) made a move attractive, I'd just go, and make a new place home.
Really, there's not so much you get in London these days (food, culture, multiculturalism) that you can't get anywhere else, and if you do need to go back, Yorkshire is only two/two and a half hours away on the train..