No government medical cannabis card exists. You need a private prescription...

https://foxtrot-wiki.win/index.php/What_Does_It_Mean_to_be_a_Registered_Medical_Cannabis_Patient_in_the_UK%3F

No government medical cannabis card exists. You need a private prescription after a specialist consultation and medical record review. You may carry an optional card as proof of lawful use, but your valid prescription is the essential legal document.