You will want a reservation for Blanton Creek. The water sites are great with lots of shade. Since this is campground on a Georgia Power lake, you should find it full no matter the time of year. As you well know, it will be hot and humid in late July, and the lake water will feel almost like bath water.
You may also want to increase your life insurance policy. We barely survived the first night there a few years ago, and it only got better thereafter. No telling who you will meet at that pub.
1976 24' Argosy
1973 International Harvester Travelette 1210 4x4 'Bernard' 164" WB
1997 Georgie Boy 30' SuperDuty v10