In my notion only "im Urlaub" is commonly in use. Another two variants could possibly be legit. But I don't know anyone declaring "in Urlaub" and I would say "auf Urlaub" is simply slang. Adhere to together with the video underneath to view how to put in our internet site https://bihlmayermedia-bilder.com/urlaub/wir-sind-im-urlaub/