We had bought 6.5 inch tongue and groove boards and asked for them to be taken down to 6 inch which basically meant removing the tongue and recutting it with the same dimensions. It's 40£ an hour so if you did the measurements for them it might shave off a few minutes!
I can't thank you enough for having done all the research on, it seems, every task I undertake in my flat :)
Did you give them a sample board to base the dimensions on or just a set of measurements?