@Clare457 I did a lot of thinking about third party bookings after several recent guests trying to trasnfer their resevation to someone else and decided that there is not much of a difference. Yes, you will not be covered by aircover which is a joke anyway. How often does something happen that you need airbnb involved? You should have some sort of home insurance and that would cover anything major.
As to the actual question you have asked, first you can ask the guest to forward you a copy as well. Nothing wrong with doing that. Airbnb is not supposed to disclose the documentation but one time a rep did. So basically only if you are lucky.