First things first, dont get goaded into the willy waving of bigger engines - you will regret it. Something like a Hornet 600 is more than enough.
I did direct access (after many years of dicking about on loads of smaller bikes) and inherited my old mans R6 - dear god its fast! No way I'd want it as a first bike if I'd not ridden before, you're simply a passenger if you dont know what you are doing. One sneeze and you'll be into triple figures followed by a bush. If you really want to learn get something small and crap to play on and learn how to handle a bike that you can chuck about. Its getting harder to justify these days, but starting on a 250cc or something similar will teach you a lot.
/dons flame suit
Anyone who says you NEED more than 600cc to have a good ride needs to learn to ride properly, as anything more powerful is just a waste in the UK. But then again, I think a GTR is too much for the roads in the UK too.