I have no idea how the CAA works and I agree that you get conflicting information, depending on who you speak to.
In the RAF I worked on Nimrod and then Hercules and since leaving have worked at Marshall Aerospace (Part-145), Agusta Westland (Part-145), Briefly at KLM (Civilian and Part-145) and most recently at Airbus Military on flight line (also Part-145)
I called the CAA and explained this to them and asked if this would be suitable and was explicitly told that the term 'Civil maintenance environment' means work carried out on aircraft that carry fee paying passengers.
What I can't understand, is that I know that permanent staff at places I've worked at have somehow managed to get licenced and I know that they only worked on military aircraft. How is that possible?