Can they only be used on the same day as the train trip.
It should be noted that the Plusbus tickets can only be purchased as an extension when buying a train ticket. They cannot be bought on their own. 'PlusBus tickets must be bought in conjunction with a train ticket and this ticket must have as its origin and / or destination the town for which PlusBus is purchased. PlusBus tickets cannot be bought on their own (except in circumstances where you already have a valid train ticket and wish to buy a PlusBus ticket for the origin and/or destination towns of the rail journey).'