What aspects of shell shock are you looking for? There aren't many official records regarding shell shock throughout the First World War, as most of it was destroyed or never even recorded in the first place. What you can look at though is Myers - the director of Psychological Laboratory who was a consulting psychologist throughout most of the war or Alfred Keogh or Arthur Slogett, who provided medical services throughout the war. The British Medical Journal will have a lot of information on them.

Additionally, the Imperial War Museum has a lot of great sources from soldiers. You'll have to do the digging yourself, but there are a lot of firsthand accounts on being homesick and shell shocked.