Bats are not dangerous to hens. They can be VERY dangerous to people. I don't want to sound like a total paranoid freak, but you should never let bats live inside a building that you enter. Only one person in the history of medicine has survived a full-blown case of rabies, and she caught it from a sick bat that she found in a church. Seriously. OK, my rant on rabies is over now.
So, now that I said that, how do you move your bats? First, you need to figure out how they get into your workshop. Holes in the eaves, loose ventilation covers, cracks near the rafters, etc. Then, find some firm hardware cloth and just after dark, when you are sure there are no bats inside, cover those holes very tightly. Small bats can fit through a hole the size of a quarter, for your reference.
If you want to be a nice and ecologically friendly person, before you do the other steps, find a nearby tree, buy or make a bathouse, and set it up for the bats. After you evict them they will relocate to that safer, happier place and your workshop and hens will be much better for it.
-MTchick
(I stand corrected. Rabies cannot be caught from feces- only saliva and blood!)