Welcome to Atlanta. A lot of good places to ride in Atlanta if you are willing to drive a little. The budweiser plant in Cartersville and Sosebee park I like a lot. I ride quite a lot solo out there and use my wahoo bolt to guide me with directions. Very safe in my opinion. Also the gaps are good if you are with a group.
What the others said about vinings cycling is spot on. Bought my Trek road bike from there and even though I dont ride with them I do like the shop.