G'day Stirfx,
boy are lucky living in such a great spot -you are in one of the most prolific areas in SA for fossils which can be found in the limestone pretty much anywhere along the river. I recently collected near Renmark and scored over 250 teeth in an afternoon. Mainly shark but there were also parrot fish plates, stingray barbs and whale bone found. There are lots of echinoids & spines of many different varieties as well as gastropods and bi-valves all which can be found by looking.
There are lots of buildings that have been built from the limestone from the area that are full of fossils. Bit hard to collect from these but they will give you an idea what can be found.
The Riverland Gem & Mineral Club with their Clubrooms in the old Glossop Hall is worth a visit. President Dennis and the members will soon give you some direction.
Be persistent and get out there to enjoy the river & what ever fossils you find.