Caught that airport train a few weeks back Edz, through to Wynyard, but it goes through the Quay. As said its the best way, though I often take a taxi as well, but the train seems quicker. The hardest part is finding the right platform at the airport, depending on what terminal you arrive at. So my tip, do some homework on the platform location in relation to your landing gate. Gotta say, Sydney commuters seem a friendly lot. Last trip there returning to the airport on the train, there was a great conversation between the dozen or so of us in that section on the Brexit vote. Good ol' Adelaidian's treat everyone on public transport as second class citizens, being the 20 minutes city and all that, and wouldn't even make eye contact let alone converse.
Cheers and hope your appointment goes well mate.
Andrew