Welcome to the forum.
The chances of getting a tourist visa can vary, it really depends on her age (is she over 21?), whether you've met in person and how many times, and whether you can support her. Having reasons to return to the Philippines (job, property, etc) can help but is not always essential when in a relationship with the sponsor (who is settled in the UK).
Don't though see the tourist visa as a cheap and easy way of being able live together in the UK, it can only use for relatively short periods of time (up to 6 months), and there is no way to convert it to a settlement visa without leaving the UK.
