we have a semi that we've been renovating on and off (and living in) for last three years. it's now gotten to the point where for what we want the walls are just in wrong place so they just have to go
we're thinking of gutting the place and rebuilding the inside from scratch. lowering the floor about 60cm (sloped block) after the first room and dropping the (currently 3m) ceilings down the 2.4m which should hopefully give us enough headroom in what was attic area for another two smaller rooms.
the attic has a headroom of 3m as well but has a pretty vicious slope on the roof so it dropped off pretty quick so there was really only a 1.5m wide strip what was useable, although it was a 10m strip. Were hoping that lowering both the floor and ceiling will extend that another meter or so wider to make it much more useable up there.
the other alternative is to knock down the whole thing down and rebuild it back to the original shell size/shape/facade which might prove a bit cheaper but could be more dangerous as it's a semi and we don't want anything to screw up anything on the other side (our neighbours).
we've downloaded the survival kit already and just have to print it out but from what we've read so far it looks good, we'd already started off the wrong way, looking for a builder, so at least we know to leave them alone for the moment and go and talk to the council instead.
i'm sure we'll have a bunch of questions and we might even be able to help others as well.