Drop in Seat Refurbishment

I have 3 chairs with drop in seats. I have painted/ refurbished/ treated the woodworm (not in that order) the chairs. The seats need recovering. This isn't a particularly tricky job but it is time consuming and means removing the old cover first, otherwise the seat won't fit back into the chair. This evening I am just removing the cover. I need decent light to cut the new fabric and fit back on the seat - and due to the electic problems I don't proper electricy until 20th November. So the next stage is a daytime operation.