The normal way to get a Licence:
Do a CBT or Compulsory Basic Training which qualifies you on anything upto a 125cc machine. (Scooter or bike, automatic or manual trans)
The CBT will cover the basic road safety elements, steering the bike, controlling the bike slowly and quickly, safe road riding, highway code, slow manoeuvres etc.. It takes a day and is typically an 'attendance course' as long as you attend and meet the different areas without being dangerous you'll achieve a pass. If you don't pass first time most biking schools offer another days tuition free.
After CBT if your over 21 you can go on to DAS or the Direct Access Scheme, this isn't the way I'm going as I'm only a young'en but this essentially entitles you to ride any size (cc) machine after passing the two part test. To do DAS you will firstly have to pass your Motorcycle Theory test. It's very similar to the car theory test but of course with a greater focus on motorbikes rather than car specific questions. With the theory passed you can move onto your Module 1 which is the off-road skills and manoeuvres part of the test. It takes around 25 minutes and your expected to perform an emergency stop, U-turn, move round a bend slowly, move round a bend quickly, park in a set area, wheel the bike around, perform a cone slalom, two figure of eights and the swerve test. The idea is that your demonstrating the ability to ride the bike at different speeds safely and perform the different movements when you have too. (U-Turns, emergency stops etc..) There is a video on youtube of everything you have to do for the MOD 1. If you pay attention at CBT it really isn't much of a step up.
After your MOD 1 you are then able to go on to the second module of the bike test. The MOD 2. Module 2 is road riding skills and is essentially like the practical driving part of your car test. Your let lose on the roads (with a microphone connecting you to the instructor) and expected to follow a set route and ride around safely. Again this normally lasts between 25-35 minutes (I believe) and is graded with Minors and Majors the same as your car test. Any Majors result in a fail. 5 Minors turn into a major.
I've just had my bike training yesterday and been told to go straight for MOD 1 and MOD 2 and been offered a part ex on my bike for a gorgeous SV650 so hoping to have my Theory done on sept 11 then MOD 1 and MOD 2 finished up that month then on to my big sexy bike