[Tsuwabuki]

It doesn't matter how many GSCES or A Levels you have. Toss on some Pre-Us while you're at it.

All that matters is the university degree. Is it a BA or a BS? You're in. Is it a two year degree? Not good enough. Three year degree? Immigration precedent goes down the middle, sometimes yes, sometimes no, and usually they want a nice long letter from your employer stating why a three year degree is enough to do the job.

The easiest, as stated, is teaching. It's the fastest way into the country, assuming you have a four year degree or can prove you can do the job with a three year degree. Teaching is probably an area where you can certainly make a case that a three year degree is good enough.

You might also look into a cultural or apprenticeship visa, since you want to go into a field Japan excels at and dictates. The downside is that you have to watch your "income" very carefully. You're only allowed to make as much as is required to pay your most basic of expenses. If you're actually accruing cash, immigration will get very angry.

You're in the UK... I think the UK gets a working holiday visa. I know most commonwealth nations do. In that case you do not have to have the degree to get the visa, but it only lasts six months, and renewals, while possible, are sketchy at best.

Best bet? Go for the teaching job to get you here, and then start looking for someone to take you on in your field, even part time, even at a no name studio.

This is work. It doesn't come by accident. It comes by persistence, connections, and planning.