I've skipped the last two pages, so forgive me if the idea has been shot down or whatever. The Mini is a great idea though, I got one two days ago. It'll be €1200-ish to insure when I'm 18, and €310 to tax for a year. They are a lovely car, especially for a first car. They're extremely personalisable, without going for Astra-van ricery. There's almost an infinite amount of setups you can make with all of the restoration parts available for inside and out, compared to bolting pieces of plastic onto an Astra.
Plus there's plenty of grunt from the engine as standard (I have the 1275, which ~80% of the ones from the 90's are), and they're easily tunable (Last issue of MiniWorld did a feature on a BMW-produced supercharger kit available for around £1300 for carbed models, for example, which almost quadruples BHP). You also feel you're going twice as fast as you really are when cornering, which is excellent fun. There's no need of doing suspension mods to them either, they have rubber cone suspension, which has about 3mm of travel
And when you inevitably do have a crash or tip, body panels are dirt cheap (My nearside A-panel has dabs of rust around the bottom edge, but a new panel is £14 delivered for example).
Why don't you wait until you're 18 before insuring your own car though? My named driver policy at the moment on a 1.0L is €600, compared to about €3500 if I was to insure it on my own. If you did get a Mini, you could let one of your parents insure it as a second car, with you as named driver. A lot of people insure Minis as a "weekend" car, so it wouldn't look dodgy. It would look far less suspicious than if you did the same thing with a modern car anyway...You still have a bike to keep you going until you're 18 if you decided to wait altogether. Think of the amount of money you could save towards petrol, tax and tyres, not to mention and mods you're planning