My personal opinion is that if you want a walk-in size coop, you are BY FAR better off getting one of the many many good step-by-step SHED building books. There are a bunch of them out there with excellent detailed lists, plans, photos, and hold-you-by-the-hand directions. Then just add more ventilation, a roost popdoor and nestboxes, and there ya go, it's better than most of the "official" commercial walk-in size coops
If you want a small reach-in size coop, the Coop Building for Dummies book (authored by this forum's owner, but a good book in its own right) is probably your best IMO.
The other ones I'm aware of:
The book by, I think, Judith Pangman (?) does NOT (despite its title) have actual PLANS, it just has poorly-measured and incomplete sketches, so if you are a novice builder you would not be able to use it very well to actually build any of the coops in the book.
There is a Country Wisdom pamphlet that is an extract from Gail Damerow's "Storey's Guide to Raising Chickens" that is not going to help you very much in terms of construction plans either.
There are a few British books on building coops that I have not seen and thus have no opinion on.
Really, either get a shed-building book or the Dummies one, depending on size of coop desired
Good luck, have fun,
Pat