You can get your certificate of non impediment by going to any british registry office to register your intention to marry in Philippines. It doesnt matter if you are foreign or not, because you will eventually be coming back to UK to live anyway. Just go along to Citizens Advice Bureau and ask them where to go and what to do. Its what they are there for ! Good luck. Apart from that i cant think of much else right now, but there are some things you need from Philippines too when you get there, but your fiance should know about that.