Wiggly,
If you go after your last exam and before the school holidays start you should be able to get a good price for a flight. Try flights4less.com. I should think you could find something for about £300, especially if you're happy to change planes elsewhere in the US, or possibly Amsterdam or Paris. You'll need to fly into Orlando International (MCO) if you're going it alone as Sanford is far too far out if you haven't got a car (see below).
You should also be able to find some cheap accommodation along either International Drive (near Universal an Sea World) or on Hwy 192 (near Disney Maingate). Try typing "Orlando Accommodation" into a search engine and seeing what comes up.
Most of the hotels, even the economy ones, offer transportation.
You can't hire a car - you need to be over 21 and have held a full licence for a year.
Alternatively, try a travel agent. Business is slow because of the war and 9/11 so you may get a bargain. We've used Thomas Cook this year for a fly drive (booked villa privately) - they've bent over backwards to get us exactly what we want.
Your big expense is the parks. They only cost a bit more per day than Alton Towers, are infinitely more impressive, but it adds up....
Hope you find something you can afford.
