Medical cannabis is legal, but driving remains a minefield. With a 2μg/L THC...

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

Medical cannabis is legal, but driving remains a minefield. With a 2μg/L THC limit, a prescription offers a potential medical defence, yet it doesn’t bypass DVLA fitness-to-drive requirements