To get hold of the CNI you need to give notice of your wedding in person to a UK Superintendent Registrar, usually in the district where you live.
As long as there are no objections to your proposed marriage, a CNI will then be issued between 15 and 23 days after your appointment and posting.
Validity is from date of Issue
You need to exchange this for local CNI at the British Embassy in Manila. There is an appointment system in operation now since 1st July. No same day service.
If you want to get confirmation of this from the General Register Office, then here are the contact details:-
General Register Office
PO Box 2
Southport
PR8 2HH
Tel: 0151 471 4803
Certificate Information line: 0845 603 7788
Email address: certificate.services@ips.gsi.gov.uk
Email: marriages@ips.gsi.gov.uk
Opening Hours: Monday to Friday from 8.00 am to 8.00 pm. Saturdays from 9.00 am to 4.00 pm
Website:http://www.ips.gov.uk