You need to do a cbt yes. This is Compulsory Basic Training....only an idiot wouldnt get through this in a few hours...its simple. Quick talk on road safety, then bike checks etc, then out on the road with a trained instructor for about 1 or 2 hours.
When you book your CBT book the lot as at this time of year they are busy as hell. Book your CBT then theory then a weeks Direct access(DAS) course. You do the CBT, then do your theory and then your direct access, usually a 4 day course or 3 if ya good from the off, at the end of the das training you do your test on the 500cc bike you have been doing training on and PASS , then you can ride any bike the insurance will allow you to