Little Hen Rescue would like to make contact with people interested in taking on ex-battery hens. They're not an RSPCA group, but they are well organised and have sensible policies on selecting suitable homes. If they are not satisfied that you would be capable of providing suitable free-range conditions for chickens, they will not rehome birds with you.
I should stress that they are an entirely legal rescue; they make agreements with farmers who are about to dispose of "spent" hens who are no longer economically viable as commercial layers.
Their next rescue event is due to take place on 29th June and they need to have enough homes to accommodate 11,000 hens by that date.
Please use the form on their website to contact them if you are interested in taking on a group of hens. They're based in Norfolk (with an outpost in Lincolnshire) and you would need to be able to arrange collection from there.