C'mon, guys, the way people are talking here it makes it sound like every time you turn the key in a Supra you take your life in your hands...! Unless you're a COMPLETE idiot right from the word go, it's a car at the end of the day. One that needs a bit of respect and time to get to know, granted, but give the kid a break...
To the OP: if it were me, I'd do exactly what I did 6 years ago and buy a stock (or as near to stock as you can find) TT6. I get what you mean about the auto'. Everyone raves about it and although I've never driven an auto' Supra, I've been for a passenger ride in a single turbo'd auto and it is indeed very quick. BUT... Like you say you don't, I just DON'T WANT ONE. If that's genuinely how you feel, inexperience or not, stick to your guns and get a manual. Yes the clutch is heavier than your average Euro-box and it can be a pain in traffic, but who cares? I love having the say over when my gears change and I don't intend to alter that sensation any time soon.
You're not going to get an NA-T conversion done for £5k either so forget the idea.
So there. Buy a TT6. They're for winners!
Good luck on the hunt (and getting insurance!!!).