Re: Need Recommendations for UK publishers
Various publishing houses have authors who are writing or have written military SF, but there is no real Baen equivalent here in the UK. Closest would be Games Workshop's Black Linrary, but they're only interested in work set within the Warhammer 40K universe.
I'm afraid otherwise it's the normal route of persuading an agent to take you on and then having them pitch the book to a publisher.
Good luck, in any case.