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

https://bizzmarkblog.com/the-motorists-guide-to-medical-cannabis-dvla-rules-section-5a-and-staying-legal/

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