First of all relax. Gestational diabetes does have risks and concerns but most of those occur when your sugar is not controlled during your pregnancy. You know about it now, so now you monitor your sugar levels (with a glucometer). You, also, follow a stricter diet that keeps your sugar fluctuations more controlled. If necessary, your doctor will put you on insulin but that is if you cannot control the sugars through diet.
I won't lie to you, it is a bit extra work. Also, as I mentioned there are a few higher risks. They probably won't let you go past your due date. This may mean that they will induce labor. Inducing labor, does NOT mean a c-section. However, please don't let a c-section frighten you. I've met many women who were induced and successfully delivered vaginally. A c-section will be a last resort if you don't want it. The reasons for a c-section would be either you or the baby are in danger, you are not progressing in labor (after several hours of labor -- usually they will let you try very long with this one), or the baby is in a breech position.
I had gestational diabetes with all three of my children. Like I said, it is a little more work monitoring your blood sugars and meals, but things went very well throughout my pregnancies. They, also, did more sonograms to monitor the growth of each baby better. (One of the risks with uncontrolled diabetes in pregnancy is that they baby can grow very large. At the same time, since the energy is put into growing larger, the internal organs, like the lungs, do not develop as quickly. Keeping your sugars controlled prevents this.) Unfortunately, I have to say that I had a c-section with all three. But please don't take this as the norm. My first child was a failure to progress baby. Her head never engaged. My doctor thinks that the opening in my uterus (those bones down there whatever you want to call it) may be on the small side. With my second child, we tried a vbac but he was an emergency c-section for something having nothing to do with diabetes (he tied the cord in a not and then wrapped it around his neck and then around his body so when my water broke his weight was cutting off the supply of oxygen and nutrients coming from the cord.) After two other c-sections and still not knowing if the head would fit through, we planned a c-section for the third. So while you plan on a natural birth, having had three sections, I urge you not to worry or be concerned about one yourself. Also, do not be afraid to ask your doctor any and every question you have. It is part of his job to answer your questions and ease your anxiety.
Good luck and feel free to email me if you have any questions or need any support as you get yourself into a new schedule of eating and monitoring your blood sugars.