>>4609802DON'T go for a corsa, saxo, clio etc (unless it's a new clio which you wouldn't get <£3000 anyway).
Insurance is a game of statistics - choose a car that not many drivers your age have destroyed and it'll be cheaper.
Obviously don't go mad - insurance for a 2.8L sports car is still gonna be insane even though the above doesn't apply.
Best bet is to go for something fairly uncommon - Rovers are good for cheap insurance because they're generally driven by old people and avoided by younger drivers (because they are kinda shit, but they'll get you from A to B and you can pick up a decent car for your money with Rover being out of business and all).
Otherwise anything with a mid-size engine (1.4-1.6) petrol or slightly larger diesel (1.5-2.0L) is a better bet, something like a Focus or old Astra.
Proof of concept - Getting quotes for a 1.1L Fiesta (55BHP), looking at £3500 for 1 years insurance (at 18 years old). Bought a Rover 45 (101BHP) and from the same company got a quote for just over £2k.
Avoid chav cars!