So - my cats used to go their holidays to MiL but she has her own cat now and I don't think they would mix.
Once or twice when we have been away overnight I have left a pile of dry food for them, loads of water, and they can come and go through the catflap. We are a bit of a trek for anyone to come and feed them.
Has anyone else left their cats for longer? How long exactly [scared emoticon]. Issue with the cattery is not the cost - it's more the distance and the fact I think they will be happier here.