Update. I have measured the bungalow now and to my surprise it looks like it is 140sq metres. Thats pure surface area, not taking anything off for doors/windows etc. So it seems that the guy that quoted wasn't far out with his measurements, but I still think 30 man/days is FAR too long for that job.

Further to the replies above, we are now looking at External Insulation, the type where they screw panels to the exterior, then render over the whole lot. I have seen some houses being done locally and I am interested to know how much it will cost. We need the place insulated anyway and having this done will give a nice regular surface for the render, which must cut down the time it takes.