A few points to add to the comments above:
Don't model the scaffolding based on modern practice, there would not be any toeboards and minimum of handrails. 1940s health and safety: if you fall off it's your fault for not looking where you were going.
Don't give the workers hard hats or florescent vests. What's wrong with a tweed jacket and flat cap?
Do give at least supervisors ties.
Do show cement being mixed on site, probably by hand on boards rather than in even a rudimentary cement mixer.
Do show loads of sand, bricks etc. being wheeled up a ramp formed from one scaffold plank.
Do show waste materials being thrown from scaffold without a chute or hoist.
Don't show too much support for the sides of deep excavations. Working in areas as risk of collapse was known and accepted.
Do show a supervisor (with his hands in his pockets) stood on the edge of an excavation just where he himself could cause a collapse.
Lifting equipment would have been much more rudimentary and you might have some fun building a Heath Robinson-like hoist system.
Don't be tempted to show the site office as much more than a wooden shed, certainly no portakabins, welfare facilities, etc.
Do show one small wooden WC hut, but perhaps with luxurious weed growth behind it ... ;-)
Don't show health and safety warning notices.
Don't worry about fencing the site: if anyone strays onto site and hurts themselves it's their own stupid fault.
Do show nightwatchman's hut and brazier. A guard dog or two wouldn't go amiss.