Welcome to BYC and a warning -- we all think we're just going to have a few hens and a small coop.
For many of us, that dream spirals into many more hens and much more housing. It's easier to go for a bigger coop than you think you'll ever need; the chickens won't mind extra space if you don't need it, and you won't have to build or buy more coop space. I won't even embarrass myself by telling you how many chickens and/or coops I have now.
Thanks for joining BYC, and by all means, let us know when you get your chickens!