I can't advise on London workmen, but the flooringis best done after fitting and befor the plinth goes on along the units (if a fitted kitchen). You can then lay tiles or floor covering just up to the inside of the 'leg stands', saving doing the wole thing, and you have a better idea of exactly what will look right nce it's in. There are one-stop fitters in our area who do the whole thing - plastering, electrics, plumbing and unit fitting - much easier as you only negotiate with one person and it's faster installation. Good luck!