The problem with 3PM K/O is that the University have their open day that day. In previous years as they use the car parks hence the Albion game has had to be moved back. N.B. I am not saying this will defiantly happen for the Cardiff game.
With the University of Sussex open day on 3rd October, The Cardiff match may have a delayed kick off to 5PM as in previous seasons.
http://www.sussex.ac.uk/study/visitus/ug