We just bought an old country property in need of work and didn't have the official survey done before going sale agreed. We did, however, bring a friend along to one of the viewing who is a surveyor, so he could eye up any obvious problems. I haven't heard of having the survey done before going sale agreed but it might be worth considering if you are serious about the property. I would wonder however what would happen if a third party becomes interested after the survey has been completed, are they privy to the information as well, that you have already paid for? It sounds a bit messy...A survey dosen't cost that much and it may be worth getting your own private survey done and then you alone would own the results.