It is therefore recommended to buy all your tickets before starting your journey. It is easy to do this nowadays using split ticketing sites such as splitticketing.com or https://trainsplit.com/.

Third-party booking sites edit

There are some third-party websites (the most popular being Trainline) that can book tickets for train travel within the UK. Given that these websites typically charge a booking fee, this is usually a bad idea, as you can easily book a ticket from any train operator in the UK (for anywhere in the UK, even if the journey is with a different operator) without paying a booking fee. There is little reason to use them, with the exception of the split-journey tickets case described above.