Rail fares information for all journeys on the national rail network is available on Train Operating Company and the National Rail Enquiries website. This also includes journey planning information. This can be used by anyone to check fares and find any split ticket opportunity.
The Association of Train Operating Companies (ATOC) who represent the rail industry make the underlying data available, free of charge, under the terms of a licence arrangement. There are now a number of websites which offer a service to search for split ticket combinations.