She got married in the Philippines and so get her marriage annuled in the Philippines!
If you marry your partner in the UK without sorting out her first marriage you/your partner might get charge of 'bigamist'.
Now I'm hoping that what I said here is not wrong.
Lady J is correct 100%. I'm afraid you'll have to bite the bullet and get your g/f to get that annullment first. Don't try to break the rules, its not worth the hassle.