cafeteria at work = (die) Cafeteria or (die) Kantine
cafeteria at school = (die) Cafeteria or (die) Mensa
Other words for cafeteria are Imbisshalle or Selbstbedienungsrestaurant (this word is made of three words: selbst = self, Bedienung = service and restaurant = restaurant. So it`s a restaurant where you serve yourself).