All a coop is, in your country, is a box with a roost pole in it. How fancy that box is, is up to you. It can be as simply as a cube with a pole that sits with the opening down and they hop up inside to roost. A great start is a Home Depot shed or a large Craigslist dog house and simply modify it for access by you and the birds.
The biggest planning issue is whether it will be totally inside a shaded secure run (with small holed tight wire, topped and skirted) or if it will be attached to the same. If it's inside, you don't need to worry about wiring the windows or a secure pop door because the run keeps the bad guys out.