I was 22 when I bought my N/A was 3.5k to insure with 1 NCB driving for just over a year. UK spec cars are cheaper to insure, as they are not imports, you shouldn't insure your parents on it, only for you to drive it as guinsy said that is illegal, best thing you can do is insure it in your name as you being the main driver then put your parents on as named drivers, this should help to bring it down quite a bit. How much you pay also massively depends on your postcode. You will defiantly need a full time job with one of these cars, I used to go through about £400 a month in fuel in my N/A used to do about 350-400 miles to a tank