Tristan, stop talking crap. You're scaring the boy! (Now I'm going to as well)
Motorsport Engineering can be a decent course, you just have to study it at the right place (and have the right attitude). You should know that, as we both went to the same uni.
However, I don't think I'd want to study it anywhere else than here, as every other uni dumbs it down with too much cars and not enough knowledge. Good if you want to be a mechanic or technician, bad if you want to do real engineering.
As such, I'd still recommend Mech. Eng. degrees at every other uni.
Sam, seriously try to get proper qualifications. I'm sure you can wangle your way into a college to do maths/physics/something else (product design/electronics?). Committing to motorsport so early shows a narrow mind, and if you ever want or need to change jobs you'll be at a disadvantage. Given how quick teams can go bust, you need to be versatile.
The absolute best way to go about it is college -> uni Mech. Eng. (MEng, MSc) degree with a year placement in industry. Any other way will be much harder, and might shut off a lot of opportunities. Big teams will only hire people with 'real' degrees to proper engineering roles, but you stand a chance as a technician/mechanic/manager otherwise.
With regards to the car, get an MX-5 or Mk1 MR2.