Medical cannabis users must be careful. While a defence exists for the 2µg/L...

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

Medical cannabis users must be careful. While a defence exists for the 2µg/L THC limit, you must still meet DVLA fitness standards. Legality isn't a safety pass: if your prescription impairs you, don’t drive