I think the date is fairly arbitrary - we calculated 3 months from our Visa application as looking at processing times we were fairly certain we would have a result at this point...
From an accomodation perspective I submitted a copy of the deeds for the house (you can get a copy online) , a couple of utility bills and council tax bill as proof of address and also the original estate agent brochure for the house which stated the room sizes and included pictures. I also made it clear in the covering letter that the house was wholly owned by myself and that my wife and I would be the only residents in the house.
Hope this helps - we were approved a few days ago so feel free to ask any questions regarding what we submitted and how we submitted it.
Steve
I have taken photos of the rooms and put a photo of us in each picture as proof. I have asked my Father to confirm this is our house and the room dimensions and my board & lodge each month, plus my bank statement shows this as my home address.
"Nothing ventured, nothing gained"
"It is better to have loved and lost than to never have loved at all" Lord Tenneson.