If you don’t have a Family Railcard, some Train Operating Companies (TOCs) offer what are known as “Kids For a Quid” promotions. To get these fares, you have to do a separate booking for the children. On the booking engine, enter 0 (zero) for the number of adults and then however many children you want to book for. It’s worthwhile checking it first to make sure the route you are travelling on has these promotional fares.