By law, the NHS ceases to have responsibility for the medical care of patients when they leave the UK. People traveling within Europe are advised to carry an authorised European Health Insurance Card (EHIC) at all times and this gives entitlement to reduced cost (and sometimes free) medical treatment. Patients should be advised to check specific entitlements prior to travel.
GPs are not required by their Terms of Service to provide prescriptions for the treatment of a condition that is not present and may arise while the patient is abroad. Persons who have left the UK, or who are intending to leave the UK, for more than 3 months are not normally allowed to continue to be registered with a practice.
The NHS accepts responsibility for supplying ongoing medication for temporary periods abroad of up to 3 months. If a person is going to be abroad for more than three months then all that the patient is entitled to at NHS expense is a sufficient supply of his/her regular medication in order to get to their destination, where they should then find an alternative supply of that medication.
For more information on taking medicine abroad:- Can I take my medicine abroad?