Chestnut jigsaw puzzle

Things are back to normal at chez peasant, i am working again the germs have gone and i am trying to solve a jigsaw puzzle in chestnut. The pieces are variable in length, width and can even taper. Somehow i have to make them fit the width of the room without wasting too much! I have managed to sort out some pieces that may do the first row and have discovered that one of the walls runs out by 9cm, that has completely screwed up my calculations! the other wall runs out by 7cm over 3m so that isn't quite so bad. Why didn't we opt to put a standard parquet flooring down rather than lay a traditional floor? It would have been so much easier, but hey that is what restoration is all about i suppose. Just to continue the "firsts" theme, this is the first wooden floor that i have laid so i expect a few swear words, nothing new there then! I only have 20sq. metres to lay in this room then eventually i have another room to do at 19sq. metres hopefully by then i might have sort of idea of what i am supposed to be doing!! When it is all down should i stain it? just clear varnish it? will it be too light if i don't stain it? should i fill in the knot holes? arrghhh i am going to retire to the cellar and try the plum brandy i made last year......... got people coming to dinner tonight so have to get the lamb ready......... I need to cut some more wood....my head hurts........the cats want feeding and the sun is coming out....