Prescribed medical cannabis doesn’t exempt you from the 2µg/L THC roadside...

https://www.bookmarking-jet.win/medical-cannabis-is-legal-but-driving-remains-a-minefield-with-a-2mg-l-thc

Prescribed medical cannabis doesn’t exempt you from the 2µg/L THC roadside limit. A statutory defence exists, but it won’t protect you if impaired. You must meet DVLA fitness-to-drive standards—a prescription isn't a safety substitute