The more expensive the coop the more secure and size. If your chickens aren't going to be free-range (let out to roam in the garden) then you need to purchase a coop with an attached run.
[header] How to set up a chicken coop [title] Purchase a suitable chicken coop for your flock. [step] You'll need to decide upon the size, security, run and price. The larger the flock, the larger the coop.