Just booked a couple of flights to Geneva from London City Airport for under £85 each in Feb half term. Flying on the Monday (16th) early morning and returning on the Friday (20th) should be able to fit in 2/4 days skiing. All other airlines seem to be charging quite a bit more than this for half term flights. Also there were no hidden charges all taxes and fees were included in the price shown on the screen.
I also noticed you could get this Price for Mon 16th to Mon 23rd if you really wanted a whole week of skiing and don't mind the kids missing a day of school.