Destroy and then rebuild "the blue room", which then might be some other coloured room, I'm not stuck on blue...

I’ll have to take a pic before I start, but above the dining room is a room which has a staircase coming up into it, 2 windows, and a door and small hall which leads to the master bedroom and the washroom. It was split into a very small bedroom and sitting room when I was quite young. It is COLD in there. The walls are lathe and plaster, with no real insulation. The attic is also very poorly insulated. The floors are in rough shape (appearance wise) as are the stairs. So I’m going to take it down to bare bones, and redo. It hasn’t been “redone” aesthetically since I was a teenager, so its due any way. So now to plan, and destroy!