What's your weight?
If you're moving to Brisbane it's likely you'll sail in Moreton Bay, either at Wellington point (flat to medium rough water) or at Redcliffe (medium to very rough water). Spring-Summer winds are northerlies and Summer-Winter winds are Southeasters. You will only need a light wetsuit from May to Sept. From Sept in the northerlies you just need a pair of shorts. We do get big days but a lot of the time we're on large gear in 15 knots.
I sail at Redcliffe, get out nearly 50 times per year, weigh 79kg and use the following gear:
Boards:
Exocet SCross Freeride 115
Exocet Cross FSW 104
Fanatic Freewave 86
Most sailing is on the big boards spread about equally. Only 10-15% of sailing is on the 86l.
Sails are a mix of freeride and wave sails 7.5, 6.5, 5.8, 5.2, 4.5. The big end of the spectrum gets used most, small end not very often. Might use the 4.5 about four times per year.
Sailing here is not consistently windy but we do have the benefit of a year-round season and very warm weather. I love the northerlies - big faultless blue skies, really, really warm, and blue water. Southerlies come through with a bit of cloud and some rain sometimes, and are a little cooler but still pretty warm. You won't know yourself after Ireland...
There's no daylight saving so it can be hard to impossible to get a sail after work unless you live bayside and knock off at 4pm or have a flexible job. If you can try to live Bayside. Getting out of the city even on the weekend can be a test depending on where you live. Do not try the western suburbs - you'll be trapped in hell (ask me how I know).
September at Queen's Beach, Redcliffe