Following part 1 and part 2, I received the official assessment a while back. Here is a quick analysis of the content and subsequent research on my part.
The Green Deal assessment I received is a 5 page PDF document. The very first thing that it tells me is that my current situation could be worse:
So my household consumes less than the typical household. This is probably due to my habits rather than the building being energy efficient: I am out during the day, I tend to switch lights off when I'm not in a room and will put a fleece on when it's a bit chilly rather than switch on the heating. The side effect of this, as the rest of the document attests, is that my saving potential is lower than average.