Different view point, but what about do your CBT then take your test on a 125cc bike. This then means that you can get rid of your L plates, carry a pillion and ride on motorways, but it is cheaper than direct access. You'd be limited to 33bhp for 2 years, but could then ride whatever you like.
You can get a 650GS restricted to 33bhp and it doesn't affect the performance that much as it is a low reving engine that doesn't rely on top end power.
I think it is a safer way of getting in to biking, rather than jumping on something big and powerful before you have picked up the riding skills.