Medical cannabis users face complex road rules. While a medical defence exists...

https://wiki-room.win/index.php/The_Motorist%E2%80%99s_Guide_to_Medical_Cannabis:_DVLA_Rules,_Section_5A,_and_Staying_Legal

Medical cannabis users face complex road rules. While a medical defence exists for the 2µg/L THC limit, you must meet DVLA fitness standards. Always remember: legality does not replace responsibility; a prescription is no safety guarantee