having been in this position myself id say weigh up your options.
you can afford the mk2, but in a years time will you be able to insure it again, will you be able to afford the maintenance and upkeep of it. and most importantly will you be able to afford to have a life.
I know many people who have fast cars, trouble is, they cant afford to do anything else. they either sit at home on a weekend or go sit with a mate in a car park because they cant afford to go on nights out, go to the cinema go on holidays etc.
when I was 17 I really wanted a mk4 gti, I had the money there for the insurance, my job meant I could afford to run it and maintain it and tax it and pay insurance the next year etc etc etc. I could also afford to go out every weekend and waste best part of £100 getting drunk, could afford to go on 1, 2 or sometimes 3 holidays a year etc etc etc and just have a life aswell as the car I wanted, therefore I went for it, people said I was mad paying the price I did for insurance, but it was only money and id only waste it on other stuff...
so my advice is if you can afford to have a life then go for it...