UK medical cannabis prescriptions don't grant international travel rights....

https://yenkee-wiki.win/index.php/Do_I_Have_to_Inform_the_Airline_That_I_Am_Carrying_Medical_Cannabis%3F_A_Guide_for_the_Anxious_Traveller

UK medical cannabis prescriptions don't grant international travel rights. Rules vary across Europe and local laws always take priority. Always pack original containers, your prescription, and a doctor’s letter. Check destination rules first.