Capt Fathom's answer is not the whole story. If a multi pilot capable (not necessarily required to have 2 pilots) aircraft has a co-pilot, is being flown in accordance with multi crew procedures in the AOC holder's operations manual, then co pilot time may be logged.
See CASA EX116/15
Of course in the OP's example of tooling around in a PVT operation, the exemption does not apply so no co pilot time as others have said.