Get a cheap run around like a micra or KA, build up your NCB for 2/3 years (hopefully) then get something awesome.
I'd rather you write off one of them then a nice VW (even mk3

)
You may feel a bit of a twit, but they do the job and as soon as you hit 20/21 insurance will be dirt cheap for you with some NCB and a bit of experience behind you.
Then you can get something awesome and be able to leave everyone your own age in the dust!