3. Where the full range of tickets is not available
If you cannot buy an appropriate ticket for the journey you want to make because the range of tickets that is available at the station from which you intend to start your journey is restricted, you must buy a ticket or Permit to Travel before you travel that entitles you to make at least part of the journey. Then you must, as soon as is reasonably practicable, buy an appropriate ticket to complete your journey. In these circumstances, you only need to pay the fare that you would have paid if you had bought a ticket immediately before your journey. The price you will have to pay will be reduced by the amount paid for the ticket or Permit to Travel.