Yesterday we finally completed the underfloor insulation in the dining room and replaced the floor boards. Just in time before the builder returns today.
Both the kitchen and the hall have solid floors which will heat up and cool down very slowly. The dining room and living room floors however are suspended over a large air gap that is the same temperature as the outside air. Having the insulation is already making a huge difference by stopping the drafts that were coming up from under the floor. Here's a photo of the other side of the room looking towards the hall.