This won't solve all your problems, but if a horse ever spooks and takes off on me, I use a one-rein stop (AKA your emergency brake.) Now it is hard, especially for a beginner, to even think to use this when your horse takes off and everything happens so fast, but I learned it in the beginning and made it a habit, and no it is an automatic response. When the horse bolts, take either your left or right rein (might be easier to use the one in the direction he's turning already) and pull that rein so that your horse's nose is darn near touching your leg. A horse can't very well run while bent in a tight circle. They may spin around for a second, but if you can practice one rein stops ahead of time (work them into your regular riding, and reward your horse with a release when he stops as soon as you apply one.) Now, this won't solve your nervousness/ lack of confidence, but it may curb the bolting part a little bit.
I believe this will help build your confidence and releive your nervousness. Once you can catch your horse before the spook-bolt-buck, you can use the emergency brake and feel pretty darn in control of him. After a few times doing this and he gets the idea that, "Hey, she's on to me. I best be good because I don't want to have my head in my butt anymore and I am getting dizzy" you will be the boss of him and that is a great confidence builder. Best of luck with your new job as "boss"