The " prevailing " current will never impact on your decision to travel on water. If you think it is too rough, it will be !
The close in current is affected by the tide... as the current will speed up and slow, but mostly runs to the south ( SE )
Further offshore you can experience no current at all, and also ripping current.
Winter months tend to have less current, overall.
The only time I have had any issues, is traveling out about due east....... with a strong southerly wind / swell and the current running to the south. Made it stand up and hitting it beam on was not comfortable.
The waters between the islands and 1770 mainland are fairly protected and can be tarversed in conditons that one might not go out in, in waters further to the south, due to their exposure directly to the SE & ESE swells.
A 20knot wind offshore 1770 is on par with a 15knot win off the Sunny Coast.
I have travelled out in 15knots and 1.5 seas, only to find it 5knots and .5 at the islands
All the above is my opinon and based on my experience. Others may have different views.
LP