I'd be in two minds.
Either you go the "sensible" route, wait another year, save some money, in a years time you'll be older, you'll have more no claims and an extra year of driving experience, all of which helps with insurance costs, but there are other factors involved in the insurance that you can't do anything about.
If you have another car to get around, and you're a student with little money, they why spend so much money when it will be cheaper next year.
Then of course, the enthusiast in me says, go for it. When I had a small accident in my first car, I used that as an excuse to buy a Mk3 16v GTI. You can always find reasons to do it.
Will you still be a student next year?
If so, you income probably won't change, but the insurance will be less of a burden.
My suggestion would be, keep using your current car to run around till you find the GTI you want (as it may take some time) but saving the money and building up the no claims discount.
Then when it gets a couple of months from the end of your years policy, check out the prices, see if it's affordable.
No point buying a GTI then sticking it in the garage not being driven because then it may need more work when you want to get it going again. Then you may well have to MOT and Tax it again having had no benefit from it.
You could however buy a project car and stick that in the garage, spending your spare time working on it, getting it ready for next year.
There's nothing like owning a GTI though