Legal medical cannabis isn't a free pass. You’re still bound by the 2μg/L THC...

https://qqpipi.com//index.php/Driving_with_Medical_Cannabis:_A_Practical_Guide_for_the_Roadside

Legal medical cannabis isn't a free pass. You’re still bound by the 2μg/L THC limit and DVLA fitness standards. While a medical defence exists, it doesn’t override impairment. Legality never replaces your primary duty to ensure you’re safe to drive.