So cool! I've been looking at getting a bike myself. Never ridden one, but here in the USA they have what they call MSF course (Motorcycle Safety Foundation). By taking and passing one of these two day courses you get your full licence and a decent reduction for insurance. Everyone here swears by them, I'm planning on attending one, if they have similar in the UK, it might be a good idea.
I hear that two of the fave starter bikes are the Suzuki GS500 and the Kawasaki Ninja 250 or 500. Apparently it's also recommended you don't start on a 600cc or greater sportsbike. Whilst you might get by, the chances are that it'll be difficult to handle with the bursts of speed and riding position (motor skills not yet developed), and since most people drop their bike once while learning, you risk damaging all that gorgeous and expensive fairing.
After getting a decent foundation on the used bike you've bought, then you can feel comfortable upgrading to something bigger, better and newer that you'll not only be able to handle safely, but less likely to damage.
That's what I hear anyway.
Apparently if you go for a cruiser/standard instead of a sportsbike then you can go higher in cc's for your first.