whatever you buy will be a sod to insure, I know it may sound odd but even the same engined car will be cheaper to insure in a low/poverty spec trim than for example a ghia.

Sometimes, its cheaper to insure a bigger car; for example when i was your age a 1.6 focus was cheaper than a 1.25 fiesta, in those days less desirable to young drivers and less crashed. I would scan the web for cars with a low insurance group.... You'd be very lucky to get insured on anything with a performance badge, I had to wait to 21 for my xr3i.

Also, be aware that lots of ins companies won't offer classic car ins to younger drivers (i now qualify at 24) you also often can't use the car for commuting if you were planning it.

Dare i say buy a solid KA or even something like a Micra and reap the rewards by saving for the ford you really want. If you can run it for a few years, get some no claims and you'll find it pays dividends with the ins. My RS 2k is about £680 now, a focus or fez is around £400....