Medical cannabis in the UK confuses many expats. You need a specialist...

https://highstylife.com/how-to-request-your-medical-records-from-overseas-for-uk-clinics/

Medical cannabis in the UK confuses many expats. You need a specialist prescription, not a card. Gather your medical records for private clinics, as the NHS rarely prescribes this. Always check local laws before you travel with your medication