Hannah,
I am not sure what the Queensland branches of SGAP are like but from experience a couple of the stalwarts of the Coffs Harbour branch are not committed to local provenance plants. I gave a talk to the branch on this issue and it was received with varying degrees of acceptance. Some members were very positive about the issue but others were not interested as it challenged their existing practices.
I still think that it is worth you contacting the local branch of SGAP but be aware that they may not always promote local provenance plants.
Greg Dr Greg. P. Clancy Ecologist and Wildlife Guide Coutts Crossing NSW
It widely varies from group to group, and most likely there will be some members more interested in local provenance than others, but you won’t know unless you ask. My group (city-St George in Sydney) is pretty heavily into local flora. Cheers Cas