I have now finished the area around the trap door and the stairwell, and I can start planning how to arrange stuff in this new reality. Note how I placed some furniture beside the stairs, to avoid somebody accidentally falling through the hole!
I moved the old dining table from the middle of the floor to the area close to the stairs; it will be a small-scale table for 15mm games and really small stuff like the Star Wars: X-Wing, Star Wars Armada, War Rocket, Star Trek: Attack Wing, and small 28mm skirmish games. I plan to have 3 tables available along the outer wall for such purposes.
I shall move the table with the tools on it to the space vacated by the old dining table, and then I shall put up the folding table, currently in our living room with the LEGO Elves terrain project, at the far end of the room.
I shall finish off this post with a new picture of the Cosy Corner with the mead bar behind the armchairs, and the stove ready for spreading some nice atmosphere.