Assuming at least one of you is of retirement age you will be able to apply to the overseas healthcare team at Newcastle for a form S1 which if accepted will entitle you and your other half to healthcare equal to a Spanish pensioner and paid for by the UK government.
When you get your S1 completed you take it to the INSS department in the area you will be living in Spain and if accepted you will be issued with paperwork to take to your local clinic who will issue you with a SIP card which is equal to any medical card you had in the UK. You will also be assigned to a Doctor.
Be aware the Doctor may only speak Spanish so you will need to organise a translater.
Even though you may be retired you might be asked to contribute towards the cost of prescriptions.
Dentistry is based on private care and can be expensive.
Don't forget that everything may change after Brexit.