Legally prescribed cannabis doesn’t grant a free pass on the road. While...

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

Legally prescribed cannabis doesn’t grant a free pass on the road. While there’s a medical defence for the 2 micrograms per litre THC limit, you must still meet strict DVLA fitness-to-drive standards