Hi Paul,
Happy to help. This link will take you to where you want to be http://philembassy-uk.org/consular-matters/legalization
I had to read it a few times before it sank in (it's an age thing!) but in simple terms it means this: get an £18 postal order made payable to the Philippine Embassy (the Post Office counter staff can print this onto the postal order for you or just write it on) it will cost you about £20.50. Take 2 envelopes with you. 1 of them addressed to: The Authentication Section, Philippine Embassy, 6-8 Suffolk Street, London. SW1Y 4HG. Make the other one registered and address it to yourself. Not sure but I think it costs about £2 (Well it is 3 days ago) to make your self addressed envelope registered.
Bang Stamps on BOTH envelopes, whack everything into the one addressed to the Embassy and post it.
It is worth noting that you CAN'T pay for the postal order with your bank card so it is cash only. Yes I know, here we are in 2013, it's 44 years since we put men on the moon and we still can't pay for a postal order with our bank cards!! Unbelievable.
Hope this helps, Good luck mate. Bill