At long last we have a floor! And a front and back porch as well.
The concrete was poured this morning and it is already firm enough to walk on. It should harden over the next few days and then the work can start on the interior walls. We went there after work today and poured some water on the concrete and covered it in plastic. That stops it drying too fast and cracking. Weather is pretty good for it at the moment too, mild temperatures and occasional rain to keep the humidity up.
Some pictures of the floor today, inside, on the front porch, and covered in plastic.