"I am going to the break room for a little while." or also "I am going to the faculty lounge for a quick dinner." So I feel you could say "break room" or "faculty lounge". If there is a stove we would probably call it a "kitchen". Anything more than a few things you would do yourself for preparing food and bigger than a kitchen or has a kitchen, we would then call that a cafeteria. If it has a pool table or foose ball table or ping pong table then it becomes a "rec" {pronounced like WRECK} (recreation) rec room.