Prescribed cannabis is legal, but the 2mcg/L THC limit applies to all. A...

https://wiki-cable.win/index.php/Is_there_a_legal_difference_between_recreational_cannabis_and_prescribed_cannabis_for_driving%3F

Prescribed cannabis is legal, but the 2mcg/L THC limit applies to all. A medical defence isn’t automatic; DVLA fitness to drive standards remain paramount. A prescription isn’t immunity—legality never replaces your duty to avoid impairment.