Buy something that won't matter if you scrape or bash or kerb
that's uber cheap on insurance as now you're a car owner you're never going to have spare cash again.
Keep it under 1.4 ( there's a lot of sense in going for a small petrol or diesel with fuel and tax the way it is) and don't add mods unless you declare them or else you'll get nothing to little back in the event of an accident.
Go for a Hatchback!!!!!!!!!!!!!!! if nothing else do this, so unbelievably useful
Go for a 5 door if you're taller than 5 foot as parking spaces seem to be getting smaller and 3 door cars have huge doors.
You're going to love this car more than any other car- but don't spunk money away on something this early on in your driving life.
Wait till you're 25 and waste it all on an impreza that you'll lose 3 grand on in 10 months cos of fuel prices and the second hand market and then have to trade in for a much smaller car.
My vote is a 1.4 5 door vw golf mk 4 - good on everything and ideal for paintball and mountain biking
Or a polo
German cars work and last and they're not built from paper mache (fiat) parts are cheap and readily available too.