I am starting a new job, and will probably car pool. If I have to stay late, I could take the train home (Shotts line, no changes needed). I have a bunch of Tesco vouchers to convert to RedSpottedHanky discount tickets. I am hoping I could buy a few Advance Singles for my trip and keep them in my wallet. If I do this can I just use them for any trip, or do they have to be for a particular date? If my plan will work, how long will an unused Standard Single stay valid for?