First off Geof, I take my hat off to you for facing up to your responsibilities.
You've found yourself in a situation that so many guys would run away from, and actually probably happens quite frequently, except that the fathers are ignorant of the fact that they have a child in a 3rd world country who could probably do with a dad.
I have a lovely boy who's mum is a Filipina, and the thought of him not being with me throughout his life would be almost too much to bear.
Anyway, as regards your immediate situation:
I can suggest a health insurance scheme that I know a few ex-pat friends of mine have used. Try looking here - http://www.omnibrokers.com.ph/
Probably the biggest favour you could ever do for your child is to have his birth properly registered with the British Embassy in Manila.
He will then be a British Citizen.
That is sooo important ! The sooner the better.
Certainly that would be my priority.
I'm sure the child won't be neglected, as that is not the Filipino way, but making sure funds go to where you want them IS going to be a major headache. Because of that I would would send very little money until you have established that it is being spent as you would wish.
The minimum (and probably average) wage in the Phils is only 4 or 5 pounds a day, so work things out from there.
You're asking some big questions here, so do keep asking, and I'm sure others on here will come up with some good advice.
Hopefully I'll come up with something else too.
Best of luck.