Learners driving a car MUST hold a valid provisional licence. They MUST be supervised by someone at least 21 years old who holds a full EC/EEA licence for that type of car (automatic or manual) and has held one for at least three years.
Laws MV(DL)R reg 16 & RTA 1988 sect 87
Vehicles. Any vehicle driven by a learner MUST display red L plates. In Wales, either red D plates, red L plates, or both, can be used. Plates MUST conform to legal specifications and MUST be clearly visible to others from in front of the vehicle and from behind. Plates should be removed or covered when not being driven by a learner (except on driving school vehicles).
Law MV(DL)R reg 16 & sched 4
You MUST pass the theory test (if one is required) and then a practical driving test for the category of vehicle you wish to drive before driving unaccompanied.
Law MV(DL)R reg 40