I moved from temporary accomodatation to permanent accomodation and they gave me less than a week to move which just wasn't possible as their was no carpet or paint etc. so I needed to do that.
My care coordinator wrote a letter for me and that was enough for my council and I got an overlap but it isn't easy to get so do be aware.
This link talks about it in more detail
http://england.shelter.org.uk/get_ad..._for_two_homes