Apologies for jumping in here, but it sounds like you need to get some experience pretty quickly. I can thoroughly recommend Simon Pavey's BMW backed Off Road Skills in Wales. They finish for the year at the end of October, so you'd have to hurry (and a lot of the places are already booked). Level 1 is a 2 day course and they do wonders for your confidence and skill level. After that I'd recommend joining the TRF and do as many rides with them as you can. There's no substitute for time in the saddle.