Staff describe bins overflowing with bottles, people sitting on each other's laps and colleagues sleeping in the office.
Once the final version is sent, it will be up to Downing Street to decide when the report is made public.
An announcement could come as soon as Thursday after growing pressure on Downing Street, the BBC learns.
Industry regulator Ofgem warns households that they should expect higher energy bills this winter.
RMT members vote in favour of strike action across Network Rail and 13 train operating companies.