Mika: I do not think that the meaning really changes. You actually can use any of these in this particular sentence and it works fine. GL On your work, GL With your work, GL At your work, GL In your work For ordinary conversation, wishing good luck any of the 4 ways will serve. by the way Mika: Good luck with your English studies. Good luck at your English studies. Good luck in your English studies. Good luck on your studies.