Adamr.
First of all, welcome to the club mate. Can I ask though how old you are?, you say you're starting an apprenticeship which would indicate to me you're quite young. Have you looked at insurance for the supra TT, let alone an 800bhp monster single.?
You have 20K saved for buying and fettling. but once you're on apprentice wages, I'm not so sure you'll be able to keep up with the cost required to simply maintain one of these cars.
The supra is a great car, and they are reliable. But that doesn't make them cheap to run. Proper care and attention needs to be paid in order to stay on top of it. I spend £150 - £200 per month on bits for my car just to keep her tip top. That doesn't include modifying.
I'm not going out of my way to put you off, but I'd not want to see you in over your head with a car you've thrown a lot of money at, to end up with it half finished and not able to sell it.