I have been to the Imperial War Museum, but I would like to go again. When I was last there - about five years ago, they had re-created a Flanders trench from the First World War. They did a very good job of it too. I am sure they would be able to give me some advice and tell me quite a lot. Thanks Rap.
I read the Milligan books, which I should read again. I had forgotten about those, because it is over thirty years ago that I read them. Indeed, he was in the artillery rather than the infantry, but there is still plenty to glean about those campaigns from those books - especially about the day to day life and living conditions of a private soldier.
Thanks for all the suggestions so far.