Just thought this may be of insterest to you:
In Sonairte Ecology Visitor Centre (Laytown Co. Meath Telephone: 041 9827572 ) they actually run a short course about having chickens/ hens in suburban gardens.
Might be worth doing before you get them, to know exactly what you are taking on.
Plus im sure the person running the course would know somewhere local to purchase hens.
I agree there is nothing like fresh eggs. My grandparents had a big farm & had loads of hens, ducks etc, i loved them as a child but the amount of Sh*T they produce is unbelieveable. Just be warned.
Thanks for all the help and advice. Will defo give them a buzz.