I went to the war museum in Ieper, Belgium and bought the Penguin book of First World War stories. Imo a great selection of fictional stories about the First world war in different aspects and written by authors during and (long) after the First World War.

Another very interesting non-fictional read is remembering war by Jay Winter, which fits within your interest about how things are affected by the World War. In this case how it is remembered and so how the perception of the war changed during the years after.