What are my rights in self defense when using a handgun?

In Georgia the law says i can carry in my car or home or place of business, to protect myself. I can carry my handgun in a bag or box to and from. I dont have a concealed carry permit at this moment, so i cant keep it in a holster on my body. Im concerned that if I was walking to my house from my car and an attacker pulls a gun on me or tries to mug me, am i allowed to use my gun in self defense? Really curious about this cause there has been alot of attacks in my neighborhood.