You supposed to get married within the 6 months of your visa, unless you have a good reason why the marriage didn't happened and you provide a very strong evidences of your relationship then you might have a good chance of getting a visa, but no one can really tell.
I think its a good idea for your child to get a British Passport than Philippine passport. Get her Brit passport while you are here in UK, just pick up a form in one of your local post office or go to this website https://www.ips.gov.uk/ , for Philippine passport you can apply anytime when you are in the Philippines.
Goodluck to your application.
