From the UK NHS site
If you're moving abroad on a permanent basis, you'll no longer automatically be entitled to medical treatment under normal NHS rules. This is because the NHS is a residence-based healthcare system.
You'll have to notify your GP practice so you and your family can be removed from the NHS register.
https://www.nhs.uk/using-the-nhs/healthcare-abroad/moving-abroad/planning-your-healthcare/Repeat UK prescriptions can only be sent to your UK address or your UK local pharmacy.
If 'ex=pats' are still getting repeat prescriptions, they must be getting family or friends to send it.
The GP's surgery is also at fault since generally, a patient is required to attend the surgery at least once every year to ensure the medication is still the correct one for their condition.
As a ‘veteran’ I can confirm that there are NO exemptions to the UK NHS rules for prescriptions.
I require some medication that is not available in Cyprus (not even an alternative) and need to get a ‘private prescription’ from Dr Molly. This I then send to UK on-line pharmacies who deliver here. (The crazy thing is the medication is manufactured in LIMASSOL but not available here)
The ONLY ‘ex-service’ NHS exemption is that a Veterans LIVING in the UK are entitled to priority NHS services for ‘military’ related medical conditions
This is also interesting
Veterans Benefits abroadIf you are a veteran living abroad, or you are serving in the Armed Forces abroad, you and your dependants may still be able to claim some benefits in the UK. You may be able to claim:
Maternity Allowance
Child Benefit
Employment and Support Allowance
Jobseekers Allowance (in certain European Union countries only)
https://www.citizensadvice.org.uk/benefits/armed-forces-and-veterans/benefits-and-concessions-for-the-armed-forces-veterans-and-their-families/