Hi Louis, lets take one subject at a time.

1. Did you yet decide which route you will target?
- Irish Passport and EEA route
- UK National Immigration Rules - Exemption
- UK National Immigration Rules - Standard Application based on £18600 income
- UK National Immigration Rules - Savings above £16000

2. For your forthcoming wedding
- Firstly, many congratulations to you both for a happy day and for a wonderful future.
Documentation needed:-

Generally, if you can be very slick and well organised with the needed paperwork etc, and your plans work out smoothly with no major delays you should have no problems getting married within a 21 day timeframe.
If you are in any doubt better organise a 59 day visa

In principle the documents you need are:-

Birth certificate - original
Passport
CNI (Certificate of No Impediment to Marry) - The CNI is available from your local registry office. It takes 22 days from time of application. It's 21 days for the 'bans'.
Present this document to the British Embassy in the Philippines in order to be issued a Philippine version called a "Certificate of Legal Capacity to Marry".
This certificate is needed for the application of a marriage license.
You'll need to book an appointment at the Embassy in order to secure this document.

You also need to obtain your own CENOMAR (Certificate of No Marriage) from the Philippines NSO (National Statistics Office) so you better include this timing contingency as well.

Marriage License - Apply for this in your fiancée's home town at the registry office. (or locality of where marriage will take place)
You might also be requested to attend the "Pre-Marriage Seminar" counselling sessions prior to being allowed to be married. Check and ask when you apply for the marriage license

After you apply for the license there is a mandatory 10 day waiting period while the marriage banns are published

To apply for the Marriage License you should consider having the following:-

Your birth certificate
Your passport
Your C.N.I.
Your NSO CENOMAR (if needed, please check well beforehand)
Your Divorce decree asbsolute (if applicable)

Certificate of 'Pre-Marriage Seminar' (if needed, please check well beforehand)

Her N.S.O. birth certificate (This should be fresh from NSO on latest type of security paper. Check)
Her Passport (or other appropriate ID)
Her Barangay clearance (if needed, please check well beforehand)
Her community tax certificate (often called Cedula)
Her postal I.D. Address
Her cenomar
Her Parents signed advice form (for under 25 years)
Her Parents I.D.