A couple of points. My wife is a Filipino. However, she has a Dutch passport. Needless to say she has a Filipino birth certificate and obviously has many family members in the Philippines. Would the immigration accept she was born in the Philippines even though she has a Dutch passport (previous marriage). I suppose she could apply for dual citizenship if it had any advantages.

You state that if a UK citizen resides outside the country for more then 3 months they would not be permitted to use the NHS facilities. Are you sure? We have a house in the Philippines but would leave a flat we own in the UK, for visits home, banking needs, family and, obviously, NHS facilities. We would, of course, be paying Council Tax and any other utility bills (standing charges) whilst away. We obviously have no set timetable as to what period of time we would stay in the Philippines, before we take a 'holiday' back to the UK. Do will still need to be concerned about NHS restrictions?