Oh no boho43 - why the delay to a month when the weather can be horrid? September is a lovely month to move.
As you are in a crunch situation where you could lose both money you have already invested and your buyer, could you stay with family, and put your items into storage short term? Not ideal, I know.
I understand about the clearing out. When I decluttered I filled many boxes which I am supposed to be reassessing. Opened one tonight and found the Wuv Luv I bought my late mother when she was in hospital. Can't face it yet. I'll photograph all the sentimental things and take them to Oxfam in Morpeth, rather than my local one. I have gone off charity shops now I have realised that most of the items are from downsizers or bereavement.
Let us know how you get on 
Book Title by Their Authors (Parlour Game)


I'm probably too late, but could you mount the cheval mirror on the wall somewhere instead? Could you hang the airers up on a hook behind a door anywhere? Or buy one of those very large plastic garden storage bins they have at Homebase? I'm still avoiding my packed boxes, can't face them after the very sad box of photos. 
