Hens can't get into my front garden, but when we had Muscovies they flew over the barn roof to get there. Hens and especially ducks will trample all over herbs, dust bathe between them, and the hens will scratch them up. I need to keep the dogs off my herbs (the cat died so that is no longer the potential problem it was) so I'm going to weave a very open willow fence around it. It only needs to be a foot high as the dogs won't jump over it, but for hens you'll need something more Colditz-y which is a shame as herb gardens are so pretty.
For my revamped bed, I have made it and put in the herbs I already had - thymes, marjoram, chives, oregano, monarda, and in the wings I have waiting rosemary, lemon balm, sage and spearmint. I have lots of mint so I don't really need more and it will definitely go in a large pot, as will the lemon balm. I'll wait until we're well into April before I plant those out and get some more unusual plants.
In fact the whole thing will have to be changed this summer as we are having a front porch built which will take a bit out of the herb bed, and the rest could be trampled by the workies.
I'm hoping for some good sunshine this summer so my herbs love it.