Medical cannabis users must manage more than just the 2mcg/L THC limit. A...

https://dlf-ne.org/can-i-drive-in-the-uk-if-i-have-a-medical-cannabis-prescription-the-reality-behind-the-wheel/

Medical cannabis users must manage more than just the 2mcg/L THC limit. A prescription offers a statutory defence, but it doesn’t override DVLA fitness-to-drive rules. Legality isn't a safety blanket; you remain responsible for your driving impairment.