Prescribed cannabis doesn’t grant road immunity. While a medical defence exists...

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

Prescribed cannabis doesn’t grant road immunity. While a medical defence exists for the 2μg/L THC limit, you must remain fit to drive. Always notify the DVLA if medication affects you. Legality is not a pass: safety remains your sole responsibility.