Navigating medical cannabis while driving is a minefield. While a medical...

https://wiki-byte.win/index.php/Driving,_Prescriptions,_and_The_%22Legal_vs._Safe%22_Dilemma:_A_Guide_to_Responsible_Decision_Making

Navigating medical cannabis while driving is a minefield. While a medical defence exists, the 2mcg/L THC limit is strict. You must notify the DVLA of your fitness. Remember: a prescription doesn't waive road responsibility. Legality isn't impairment.