I'm in the process of putting together a similar look (tea stained painter's overalls!) for a 1940's railway weekend coming up soon. I'd love the full on official uniform but that will take me much longer to pull together and I need a cheaper option for now. Talking of which Gressenhall are doing a Land Girls exhibition at the end of August and I plan to go along for some research!
As well as the Women's Land Army there was also the Women's Timber Corps. Or the "Land Girls" and the "Lumberjills". Their uniform was similar with brown jumpers and they provided the wood used for manufacturing and energy production.