the main pit falls are they will attract rats, as well as mice and of course foxes, Ive just got 30 hens in the past few months and their great, I get about 5-6 dozen eggs a week from mine thinking back to when I had only 6 hens they gave me 3,4 or 5 eggs a day, what you have to decide is does the cost of keeping them justify the cost of building their home and run, making it vermin proof, and with the cost of feed is going up by the week or so it seems, you might be better off finding a local allotment holder who will sell you the free range eggs you need for your family, most allotment holders sell their eggs from £1,50 - £2 a dozen, hope this helps, dont be put off by all the expense and building work needed to house the hens though, mine give me hours of pleasure, and theres nothing better than your own fresh eggs every day, good luck, let us know how you get on, steve