I see what you want to do, get your visa in advance, so after you get married you can all travel to the UK together. May cause you a problem as when you renew your visa in the UK they may question why you have a Philippines marriage certificate. Just wondering what would happen if you got married again in the UK (would only need to be a quick civil service)?
You are really best to do it the right way - how long is he planning to stay in the Philippines when he next visits? This will determine if you have any chance of getting married and than applying for and being granted a spouse visa.