Hey HAAK, you'll have to drop by on the way through.
Regarding Cactus and most West Coast surf spots, if there are surfers in the water it would be recommended to wait till they are finished. The locals are extremely protective of their breaks and have been known to get violent from time to time. If you do score, don't go telling the locals that you'll be back next year with 25 of your mates either.
There is awesome spots all the way along the coast. May pay to drop Whyalla or Port Lincoln on the way through for some tips from the locals.
Cheers Croc