Seeing that both Graham and I are going through the process of getting our little ones British passports right now, I agree that having the baby here will be the best option, not only for Shey and the baby, but for application purposes also. Applying from the Philippines is a nightmare and will take up to 4 months, unless they decide to hold things up because the passport office require more documents than they actually state on the forms or on their website.
If you can hold off going I would certainly do it, just to save the utter shambles in dealing with the passport office.
But, if your baby is born in the Philippines it is ok, the birth is registered there in the hospital and a birth certificate can be collected as normal.
Not sure Graham where you get the 500 quid registration from? 
I don't know anything about that and have never paid for any registration for my three.
If you decide to have the baby here, then you can go to the passport office in London or Liverpool and pay for the express service (have to book it online) and as long as you have all your papers, you can walk away with a british passport in 4 hours.
BIG CONGRATULATIONS btw
