I'm not sure the RAAF pilots will be converting to type in 8 weeks though. Nor that you could take RAF VC10 pilots out of their 4 person flightdeck and convert them to a modern type in 8 weeks. You're arguing apples and oranges.
The problem with the AT fleet lies in the delays of the FSTA project. But that is where the solution also lies - the contract has been signed and there's no money for an interim solution. Except more charters offset by less use of the Brize Norton Vintage Aircraft Society.