Medical cannabis users have a statutory defence, but don't get complacent. You...

https://evpowered.co.uk/feature/medical-cannabis-and-uk-driving-laws-what-ev-owners-must-know/

Medical cannabis users have a statutory defence, but don't get complacent. You must respect the 2μg/L THC limit and notify the DVLA of your fitness to drive. Remember, legal status isn't impairment immunity; your safety duty stays firmly with you.