[jasonbvr]

I think you would probably want to do at least your first two years of university studies in the UK. Because even if you do come over and study non-stop and some how pass the JLPT level 1 to get into school, Japanese students cover a lot more than other countries at the high school level. I would have to say as well that you are going to have to be fluent in Nihongo, I mean like tons, upon tons of kanji and their combinations.

Visa, I would assume you would have a student visa so any work you take one will have to be for cash. Also if you are caught working in Japan without a working visa, they will fine and deport you.

I am not trying to discourage you and don't have all the facts about studying in Japan, but it's not like Japan is going anywhere. It will still be here when you finish your degree. A possibility would be to complete part of your studies, Japanese in particular, here and then return to graduate from the UK. Then get a job and make the move. Ganbattene, ja ne....