Hi dom
There's a few people on here from around Nottingham. We'll have to go for a ride once you have your licence.
Best place for facts and figures is the main
zxrworld.co.uk site that this forum is part of. There's a huge amount of information on there. If you've got any specific questions you can't find answers to then shout out on here.
As you're under 21, you will be restricted to 33bhp for 2 years from your test pass (although a 33bhp ZXR should still be a lot quicker than your car!). This is almost always done by putting restrictors in the carbs - basically four large washers that restrict the airflow from the carbs into the engine. They are easy to put in and even easier to take out.
You don't have to restrict it using an 'approved kit' or have it fitted by a dealer. The important thing is that the bike doesn't make more than 33bhp. You've got two choices.
a) Buy an approved kit, get it fitted by a Kwak dealer, and get the certificate to say they've fitted it. I don't know what it costs but I think it's between £150 and £200.
b) Either buy or have made a set of restrictors (someone on here will be able to tell you the size you need) and fit them yourself. This will cost a fraction of option a), but you don't have a handy certificate to wave in the unlikely event that you had to prove it is restricted. Some people have suggested getting it run on a dyno with the restrictors in and having the readout as proof that it doesn't make more than 33bhp.
Actually, there is a third choice, which is don't restrict it at all. People seem to get away with it but remember that you then aren't riding in accordance with your licence (basically you are riding without a licence) and you wont have insurance (because your insurance requires you to ride according to your licence). Basically don't - 33bhp will still be quick, and you'll have something to look forward to after two years.