People often moan about high insurance prices but there's a few tricks to get it cheaper. When I was 18, I hated my 1.1 Fiesta and bought a BMW 3 series. Most people told me I'd never be able to insure one. The insurance for it was actually cheaper than the renewal quote for my Fiesta... (£700 in 2005) The reason? Probably because the older Fiesta's are stereotyped to be chav cars, thus, they probably have a higher accident rate.
I also have a friend who had a Mini Cooper S (new shape) as a first car when he was 17. He got his insurance relatively cheap by being a named driver on his parents policy. (the car had to be registered in their name however) IIRC, he paid less than £1000 to insure it, and he still earns NCB's.
It's also worth pointing out that many third party fire & theft policies are often more expensive than fully comprehensive policies. Make sure you get quotes for both. This is pretty much always the case with Direct Line and with some of the other well known insurers. Crazy, I know.
Only use price comparison sites to get a rough idea of who provides the cheapest quotes. Once you've shortlisted some suitable insurers, get a quote with them directly. Most price comparison websites earn commission for each sale, so it's often cheaper to purchase a policy directly with an insurance company.
Rich