Take your pass plus, buy something with an engine smaller than 1.4, add someone like your mum or dad as a named driver and keep scouting for quotes.
Young lads are, apparently more likely to have serious accidents than any other drivers so until you are 25 and have some no claims under your belt it'll be more expensive. Something like a Corsa, 106, Metro, Fiesta etc are cheap to insure, just don't put some silly body kit on them...