Stu, how about making it all the way to Charlwood without getting cramp. Or how about taking in a few longer rides with more hills. That could be your next challenge. I will be going out for longer rides over the winter, and they won't be particularly slow either so I think you would probably quite enjoy that especially the speed at which you seem to ascend.
But, I would also say that if you get your licence for free I see no reason in not racing at Hillingdon. You may get your butt kicked the first couple of times but I reckon you will get used to it after a bit and it won't take you long to be able to keep up. I will send you some tips by PM.
Cheers
Marek....