Pilot Lad - If I were you hold out for the cadet schemes! There seem to be more and more around, and more in the offing! Although things seem good for the current cadets going through the original wings course as well. The courses run once a month and are a mix. You get people on the wings course mixed in with BA FPP and MPL guys for the ground school, although some courses are now doing both ATPL Theory and flying in New Zealand (these seem to be the MPL guys).
In respect to your hours, it completely depends on what your hours are on/when you got them/ if you want money off. I know of several people who have significant hours (200+) some of which aren't allowed to take a reduction in hours for the course, or who have chosen not to! After all its a flying course - why would you not want to fly! 100 Hours would definitely not hold you back from the Wings course, but I can't speak for the mentored schemes. Saying that I do know of people with PPL's plus experience on Flybe Wings and BAFPP.