You must complete the CBT which is straight forward. (Enjoy it, Remeber it's a training course Not a test)
You must then take a Module 1 test, (11 Exercises, Slow ride, Slalom, Figs 8, Emergency braking and the much talked about "Swerve" Test
Module 2 is a 30 min road ride, 3 questions about your machine.
Pass both you then have a full motorcycle licence.
Your age, If you are under 21 yrs you are only allowed to take the tests on a 125cc machine, Then you can ride a bike of any size along as the power output does not exceed 33bhp ( Most bike bikes require a restrictor fitted to meet this.)
If you are over 21 yrs you can take Mod 1&2 on a bike over 500cc and then ride a bike of any size/ power output (No restrictor required(Direct access)
Hope this Helps.