There’s no official government medical cannabis card in the UK. Access requires...

https://wiki-cable.win/index.php/What_Should_I_Do_If_I_Get_Questioned_While_Carrying_Prescribed_Cannabis_in_the_UK%3F

There’s no official government medical cannabis card in the UK. Access requires a specialist consultation and review of your medical records to obtain a prescription. A clinic-issued card is optional, serving simply as helpful proof of your lawful use.