Medical cannabis prescriptions aren't a road pass. You’re still bound by the...

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

Medical cannabis prescriptions aren't a road pass. You’re still bound by the 2mcg/L THC limit and DVLA fitness standards. A medical defence is no substitute for your duty to drive safely