Healthcare for mid 50s and late 50s

You will not be covered until you reach retirement age and only if they continue it after Brexit.  You have to have private cover in place and pay the premiums which will depend of course on your health background.

You would be covered by Spanish healthcare if you started working here on a contract or started your own business.  In either case Autónomo would be paid (by employer if on contract, by you if you start own business) which then entitled you to healthcare.

Thank you for your helpful advise, very much appreciated