In Fayette co (about 20 mins south of the airport) we have a U-pick it. They have tons of fruits and veggies almost yr round for you to pick. Not sure about peaches though.
Directions from I75 at the airport would be;
continue about a mile past airport exit on Riverdale Rd continue on Riverdale Rd until you get into Fayetteville at the town square in fayetteville turn right at the first light go about 5 miles down and the U pick it is on the left side of the road. If you hit peachtree city you have gone too far.
I can also give directions from I 85 if you need them. Good luck and have fun here in ATL. It has been real rainey here the past month, you may want to bring an umbrella. *8+inches of rain this month!!!