Being a medical cannabis patient provides a statutory defence against the 2μg/L...

https://www.first-bookmarkings.win/ev-drivers-using-medical-cannabis-have-a-legal-defence-against-the-2mcg-l-thc

Being a medical cannabis patient provides a statutory defence against the 2μg/L THC blood limit, but it’s no free pass. You must still meet DVLA fitness-to-drive standards