Legally prescribed cannabis doesn’t exempt you from the 2µg/L THC limit. A...

https://www.bookmarking-maze.win/medical-cannabis-is-legal-but-the-2mcg-l-thc-limit-is-a-strict-roadside

Legally prescribed cannabis doesn’t exempt you from the 2µg/L THC limit. A medical defence exists, but you must still meet DVLA fitness-to-drive standards. Legality isn't a substitute for responsibility: being ‘legal’ isn't being safe