If I don't remember wrongly, they sent out forms fairly early last year, around March (?) asking for photos for uni card and room preferences (with a due date of start of July, I think, since I remember sending in mine almost at the deadline!).
Please send in a decent looking photo for your uni card, you're going to be living with it for the next few years... I made the mistake of sending in a really weird looking photo which looks nothing at all like me! =(