if you just want basics, bread and beer, some of the service stations are 24/7, you will probably pass a few on the way, i am not 100% if they are open,(never done a sunday) however there is a couple on the rm23 just prior to the mazzaron north turning, which are definately open on a sunday, takes you ten minutes out of your way, or you pass them if you come alomg the toll road,
cheers ant