Employment for members of the Armed Service and other Crown Service is covered (from memory) by sections 191-193 of the Employment Rights Act 1996.
The act, and other legislation, is available from HM Stationery Office:
http://www.hmso.gov.uk/acts/acts1996/1996018.htm
European law may provide some interesting ideas, but I believe not all elements have been encorporated into UK law. Suggest a Google search for those that are interested...
SBW