Once you've done your CBT, you'll have to take a theory test, to prove you've got a grasp of road signs and the theory behind staying alive on the road. The only exceptions are for holders of full moped licences (but only those obtained by passing the two-part theory/practical test itself).
The test consists of 35 multiple choice questions chosen from a list of 300 or so. Most bookshops and libraries now stock books that give you sample questions and answers, and will help prepare you for the real test. Once you've passed, the certificate is valid for two years. If you don't get a full licence in time, you have to retake the theory test. You don't have to take the theory test immediately after CBT, but it's a good idea - you cannot apply to take your main test until you've passed the theory test.
You can book your theory test on line by consulting the DSA web site at http://www.dsa.gov.uk or by telephoning their national centre on 0870 010 1372.
The DSA also provide a mock theory test which anyone can try out on their web site.
There is a wealth of information on beginning motorcycling at http://www.begin-motorcycling.co.uk.
Information reproduced from "What Bike? and Scooter" (summer 2002 issue).