Prescribed cannabis is legal, but the 2µg/L THC limit applies to all. A medical...

https://www.primary-bookmarks.win/prescribed-cannabis-is-legal-but-the-2mcg-l-thc-limit-applies-to-all-drivers

Prescribed cannabis is legal, but the 2µg/L THC limit applies to all. A medical defence needs you to be unimpaired. You must tell the DVLA of your fitness. Legality isn't immunity; you remain responsible for safety