Yeah sounds like a good idea mate, and you can still have plenty of fun without needing 150bhp to pull your arms off!

Another brilliant bike is the aprilla rs250 i'm not sure if you could ride one of them on a cbt if it was restricted I dont think you can, I think you need the 33bhp test done for that.

Best of luck with your biking days mate, and dont skimp on your clothing and helmet etc.