A new timetable begins on Sunday 14 December.
The timetable includes changes resulting from the launch of the Thameslink Improvement Project on Monday 23 March next year, which will add some 4,000 seats to peak period metro (suburban) services.
Some mainline trains will get additional coaches to relieve crowding on busy routes.
The new timetable also marks the transfer of Tonbridge - Redhill services to Southern's franchise.
The timetable will run from 14 December 2008 until 16 May 2009.
Copies of the new pocket timetables are also available from your local station and help desks.
For all other journey planning information, please consult National Rail.