I'd suggest that you do both level 2 and level 3 in facial units if you want to continue expanding the range of advanced facials.
If you think that long term you would also like to offer manicures, pedicures, waxing, make up & eye treatments then enrol on a full level 2 beauty course.
Once you have level 2 beauty you could then move onto a level 3 beauty course which would add massage, face & body electrical treatments - all of which is sound training in the electrical side of treatments. Electrolysis is another specialism you could add later.
I went into beauty after nursing (RGN) and although you get a huge amount of human biology knowledge on your nursing qualification, what you learn on a full beauty course is in far greater detail with regard to skin, skin conditions and nail conditions.