From 1st March 2014, the Consular Section will issue a new-style affirmation or an affidavit to marry. Local authorities have confirmed that they will accept this document. This replaces the old-style Certificate of No Impediment (CNI).

Here's the publication in PDF format called MARRIAGE IN THE PHILIPPINES - (Explanatory Notice to British Nationals Contemplating Marriage in the Philippines)

Don't forget you'll still need to book an appointment at the British Embassy