There is no "official list" of conditions for medical cannabis in the UK....

https://xeon-wiki.win/index.php/What_Should_I_Ask_a_Specialist_About_Medical_Cannabis_if_I_Have_Fibromyalgia%3F

There is no "official list" of conditions for medical cannabis in the UK. Instead, eligibility depends on a specialist consultant’s clinical review. You generally need to show that other standard treatments haven’t worked for your symptoms first