I posted this on an old thread but I found this article about whether you can use a loft as a bedroom:-
Loft Room as an Extra Bedroom? The main reason for converting a loft is to create a functional space. For some households this space might be just that.
www.greaterlondonproperties.co.uk
I'm not an expert but I think it fails the following:-
"Headroom: part K of current Building Regulations will apply here as, despite the fact that the room will be mainly used at a horizontal level for laying down and sleeping, the room itself must offer sufficient headroom for movement around the room. Current stipulations require adequate headroom along the complete length of one side of the bed, without the hazard of hitting the ceiling."
"In all cases, an escape route must lead from the loft room all the way to the front door and include....
... A proper staircase, definitely not a ladder
....Headroom of 2m (minimum) along the whole escape route
... The fitting of a fire safety door, which can be opened fully, as access into and out of the new loft bedroom"