I believe only one of the bolts is connected to the chassis. The others are connected to the shell. My plan is to put low profile bolts back in the holes (threads) and paint them BRG to match my car. I can't think of any other way to fill the holes short of bondo, which I do not want to do.
I will purchase the parts from a Caterham dealer. They're readily available. The parts are the fender (fiberglass or carbon fiber), cycle wing stays and headlight brackets. From a discussion with the dealer in Colorado the process is pretty straight forward.