Using prescribed cannabis as a driver requires caution. While a 2mcg/L THC...

https://dlf-ne.org/can-i-drive-in-the-uk-if-i-have-a-medical-cannabis-prescription-the-reality-behind-the-wheel/

Using prescribed cannabis as a driver requires caution. While a 2mcg/L THC medical defence exists, you must still meet DVLA fitness standards. Remember: legality doesn’t replace responsibility. If you’re impaired, you’re liable