their coop doesn't have to be a "coop" either... anything you havethat can shield them from the weather and help keep their body heat in...
a larger rubbermaid tote can be set up for them.. cut a walk though door in it, and cut a whole in both ends just big enough to put an ald sprinklter pipe through for a foost...
mine all free range, and have since they were old enough to be outside... but when it started getting clsoe to freezing, i had a kids picnic table, and some plywood and bricks.. i stood the plywood up with various things to keep it vertical and then draped an old comforter between the two pieces and over the picnic table and i moved them all from their regular roost on the fence to under the table/tent and they were fine....
do the best you can... if you can putthem outside during the day and bring them in at night for a few days it's a nice beffer between the two temps too...
good luck