Hi John,
I found records about my 3x great grandfather who was a medical store-keeper at Kertch in the Crimea in 1856.The records are kept at the National Archives,Kew,London.Most of them are in the WO series.(ie.War Office).You can look at the online catalogue and just write in "crimea" and it comes up with about 600 odd document files.Better probably to enlist help from the staff.(which you can also do online)Do you know where he was stationed ?
If you need more help let me know.