How do I find a flat to rent before moving to Edinburgh?

So my wife and I are moving to Edinburgh in a month and are having a difficult time securing a flat. When we were over in December we tried to make connections with letting agents but were told it was too far out to talk to us. Now when we try to look for places we either get no response to our inquiries or are told that we have to view it before they will discuss rental. I realize the process is different in a new land, but we are used to operating via the internet and being able to make arrangements remotely. As we get closer to our departure time our need to plan is causing a great deal of anxiety since we cannot seem to get any help or guidance. We have great references and are willing to pay up to a year in advance to secure a place. Any ideas? Also, we have 2 cats and have noticed when trying to even get something short term for while we look that people seem to be anti cat. Any ideas as to why that is? They are indoor cats, older, fixed, and also have good references. We have offered additional deposits, etc. We are just getting to the point of frustration. The University has been as helpful and responsive as the letting agents we have contacted. Any help would be greatly appreciated!