He added: "After a year, if it all fails I'll go to university and people will say 'you're that bloke from Fame Academy' and throw rotten vegetables at me. But at least I'll have got a degree!"
David told our entertainment show Newsround Lite that he'd heard rumours that part of his prize might be a cameo role in the next Harry Potter movie.
"I know some people might say you're a 24-year-old man. JK's great. Haven't seen the second film yet. I have to admit that I've got my fingers crossed. It's just a rumour. I have no idea."