The workers are called "reporters," whether what they write is "news" or not. So you could use "press room" if you didn't like "newsroom." I would think of "office" as pertaining to the business part of the magazine (advertising, purchasing, circulation, and so on).
But if you want to be exact, you need to wait for a reporter's comments.
Intriguing question, herut! Googling - at least my googling - only throws up specifics, like "worked in the art/features/entertainment department at [magazine x] or "worked on the editorial staff of [magazine x]".
JazzByChas, it could be a men's magazine as well (please disregard the connotations), i.e. a magazine, where news is not the main focus. I'm not trying to dictate what a women's magazine should be about.
Old Novice, I don't think "press room" quite works for me either. Because I do not want to focus on the reporting aspect of it too much, more so the workplace as a whole.
Loob, yes, it seems to be a bit tricky. Hopefully someone comes up with something!