Col - in a nutshell, the answer is no.
All of the C17 sims are run by Boeing. They sell their sim hours to us. That would be the case even if we had a sim here in the UK. It is already a crew-intensive business using the sims in the US - 6 days away for a 2-sim schedule. Using the Aussie sim would amplify that. It would also strain our already restricted T&S budget to breaking point!
Whilst a nice idea to post RAF instructors there, all instruction in the sim is done by Boeing staff, apart from a week at the end of the OCU. In the current climate, I can't see posts being created unnecessarily.
As the UK C17 numbers grow, it is a safe assumption that a UK C17 Sim is under constant review. The NATO C17 program in Hungary can only help our case as Boeing may now also have further Europe-based customers for a UK sim.
It's a simple case of supply & demand.
Uncle G