Adam
I'm an Sgt instructor in the ACF.
I have an Osprey Mk4 MTP Plate carrier and to be honest its just to dam heavy even with the soft plates taken out(this is now for sale on ebay.
I now have a Disciple Battle belt, with My Mk4 Osprey pouches on it along with A new issue Bergen and side pouches, Also on the Bergen it has MOLLE straps I have put on a couple of UGL pouches on here(as they are larger than the utility pouches and have a useful Velcro divider).
I have found this more than enough for my Fieldcraft weekends, and on Annual camp I will just use my DPM short back Bergen with an MTP cover on it.
AS an instructor you will be issued the new PCS kit, I have bought an extra set, along with a UBAC's and bush hat.
The Lowa desert boots are a must as the ones you get issued are only good for fieldcraft.
If you need to know more Ie lesson plans etc drop me a PM as I have loads of info and lesson plans I can help you with.