Are you flying back to the UK for good, so that your travel from South America to the UK is one-way? If it is, it may well be difficult to get two Qantas sectors in on that trip.
Thanks so much for your reply. Yes I'm afraid the trip from South America to the UK is just one way. Looks like a quick trip to Dubai is on the cards, only ever been in the airport, so will probably make a small trip out of it and stay for a few days. After I've got my status I may look at seeing if AA or BA would match the status (if they still do that) as that may be more beneficial being UK based than QFF