There is B.T. Brown Reservoir in north Coweta County. You’d need some sort of watercraft….ie…canoe, kayak, float tube. You might check out the newly opened Chattahoochee Bend State Park in the west end of the county. They have a boat ramp/canoe launch but not sure about wadeable shoals.
Also check out Sprewell Bluff Park in Upson County. There is wadeable section of water there for shoal bass on the Flint River.
On a side note….you can go to Callaway Gardens and rent a boat/trolling motor for about $35 dollars. You’d be fishing the main lake there.
If you are learning to flyfish….I’d suggest contacting Unicoi Outfitters in Helen, GA. They have a “Gilligan’s Special” that includes a half-day instruction and time on their trophy water for trout.
Sorry I can’t come up with anything more local.