Two of my ancestors served in the Crimean War, one went on to serve in the Indian Mutiny.
I no longer have a FindMyPast subscription, so I cannot, unfortunately, view the documents that others have found.
The UK, Military Campaign Medal and Award Rolls, 1793-1949 dataset on ancestry lists two John Normans with the regimental number 5122.
One served in the 1st Battalion, Scots Fusilier Guards; the other in the 1st Battalion, Coldstream Guards. Are you certain that your John served in the former? I'm sure that I can see an Essex lad being recruited by a Scottish regiment.
There are also 16 other John Normans and a John William Norman, who served in a
Anyway, by researching the regiment's activities during the war, you can develop a very good picture of what he must have experienced as a very young man