That looks like it will work well. DO you have one window? Will it be open for cross ventilation with the door? My 2 cents is to have at least one other window that opens to keep well ventilated. We got our windows out of a dumpster but recycle centers usually have good stuff. Will your compost be in the pen? I wasn't sure if you were going to stage it in there or not. Chickens do such great jobs at composting you may not need a separate area. It looks good from here! It's so exciting. Our greenhouse/chicken coop also known as the "palace" has its 4 sides up and we are putting the rafters up this weekend. YYaya.
P.S. I don;t know if you have your wood yet but my DH got super deals on returns from Lowes. We have had to hardly buy anything at full price. The universe provides.
Rachael-mother of all.