hello fellow filipinos here in UK!!

Im a nanny here in London, i dont have papers...my employer does know my situation...there's no problem about that until the family decided to have summer vacation in CORNWALL. I need to come with them via AIRPLANE.
Although it will be only a domestic flight, i told them i have worries for we'll go to GATWICK AIRPORT and do the usual stuff minus the immigration. Though the airlines told us i only need to present a ID with photo not necessarily my passport.

im terribly confused...one side of me wants to find out if i can travel via plane to go to diffrent places and not be contained just here in LONDON. one side of me is thinking it is not worth to risk. Im with the family for almost 5months and i dont want them to regret employing someone without paper...

Please help....