You can drive a motor tricycle of any power rating if both of the following are true:
you’re over 21
you have a full car driving licence
You’ll need a full category A1 motorbike licence to ride motor tricycles up to power output 15 Kilowatts (kW), and a full category A motorbike licence to ride trikes with a power output more than 15 kW.
It’s necessary to have only a car licence or to have a bike licence to drive a trike?
Maybe Longrider can help out here?