You didn't state what kind of clays you are shooting. Is is trap, skeet, or sporting clays? Shotguns are set up differently for each of the disciplines. Trap guns shoot higher than skeet, or sporting clays. If it is skeet, or sporting clays that you will be shooting, you will need the over/under.
Welcome to the sport of shotgunning, you will have a blast.
I will be shooting sporting clays. I was hoping I could use the Beretta 390 semi-auto. From what I have read on FR, this gun got pretty good reviews. But, if I would be better off with an over/under, I better start saving my pennies. Any recommendations?