Another couple of things to note on the matter of the restrictive covenants I talked about earlier:
It is up to the person with the benefit of the covenant (the person who doesn't want to be disturbed by noisy critters, etc) to enforce the restriction. So, if the covenant was first written in a deed way back in 1930 or something there is a good chance that original seller (who had the benefit) is no longer around. A neighbour who objected wouldn't necessarily be able to do anything unless they happened to know who the successor to that original beneficiary is.
If the covenant is from a newer deed - like if you have bought under a Right to Buy scheme from a Housing Association or Council; or if you are renting from the same organisation - then you may have a chance. Those transfers or leases tend to be of a standard format with entries in them designed to cover all sorts of situations so that a whole new deed does not have to drawn up forevey sale or tenancy. It would definitely be worth contacting the seller or landlord and asking for either the covenant to be modified/cancelled (this is a legal matter but not complicated) or for permission if renting.
In such a request give as much information as possible (set-up,number of birds, etc) and if you can try and find other local henkeepers who could provide a statement, including their neighbours who could possible vouch for how quiet hens really are (roosters are, of course, a different matter).
Anyway, I hope this helps. As I said earlier pm me if you want any specific info that I can help with.
Now I have to go put my girls to bed - they do like to watch the sunset.