You can ride a moped on UK roads.
Under the following conditions:
You must ride with L plates.
You are not allowed to carry a pillion passenger.
You are restricted to mopeds (geared or automatic) with a power output of less than 4kW and an engine size of no more than 50cc with maximum speed of no more than 45km/h (28mph).
You are not allowed to ride on motorways.
The CBT certificate is valid for 2 years.