Armour bridge is the closest to both those areas since your coming from the north. Its a nice Ga Power ramp with a $3 launch fee. You'll take Linger longer road off hwy 44(between the lake and I-20) and then turn left on Lake Oconee trail and then another left at the guard shack, just tell the guard your there to use the ramp. There are signs you can follow once you hit linger longer as well.

Good luck