Urgent questions don’t appear in advance on the Order Paper, because they are not granted until the day itself. If your application has been succesful, the Speaker’s Office will contact you to let you know.
If the Speaker decides not to allow an urgent question, you shouldn’t make any reference to that decision or to the submission of the question itself. It is not possible to provide feedback on unsuccessful requests.
If the Speaker allows the question, notice of the subject of the question is given on the annunciators (the monitors around the parliamentary estate) and on Twitter (@HouseofCommons).