I'm sure you know that there are RAF AT co-pilots who have successfully converted to type with about 200 hours total time, straight off their King Air wings course.
They have been role trained for both Transport and AAR over the first year or two of their Squadron careers.
The A330 will be an easier a/c to operate in these roles due to its state of the art electronics and handling, over the present 'clockwork cockpit'.
The biggest problem seems to be keeping role recency and flying hours up in the present circumstances. Only two main destinations, requiring local base flying, and empty aircraft European crew training flights.
Civilian A330 pilots would normally get 400 to 600 hours a year airline time to multiple destinations..
AirTanker are going to have to work with Military crews some at present getting less than half that yearly experience.
Any 'civilian' Air Tanker crews would have to operate to JAA rules with ATPL licences and crewed separately from the military flying. An expensive set up compared to the RAF, as civilian salaries for these types would have be in excess of £65000 for a Capt. to tempt pilots from an Airline.
A joint crewing with RAF crews studying and obtaining the civilian licences in RAF time to operate the A330, would probably mean RAF career retention problems!!
Loco Captains get about £100k per annum by the time you include flight/duty pay, but will do just shy of the maximum 900 hours. Legacy carrier pilots on wide bodies will do about 750 hour for a gross pay of £120-150k, depending on company and seniority. That's the sort of money AT would need to be matching if they want experienced civvies, and I can see that becoming a major bone of contention on a mixed civvy/RAF Sqn.
I am concerned if they just want civvy crews to fly the aircraft on wet-lease sub charter to airlines. I really don't think it'll work. These aircraft are going to have significantly more weight and drag than standard A330s and in these times of high fuel costs and great excess fleet capacities of airlines all around the globe, I can't see AT offering competitive sub charter rates unless they fly at a loss. It might be cheaper to AT than having the aircraft sit around unused, though.