No trains will run on some key routes on the Southeastern network today due to engineering works.
Buses will replace trains on all services that usually operate via Tonbridge, the company said.
The affected lines are between Sevenoaks and Paddock Wood (calling at Tonbridge) and Sevenoaks and Tunbridge Wells (calling at Hildenborough, Tonbridge and Tunbridge Wells).
Southern trains on the Tonbridge to Redhill line will also be replaced by a bus service between Tonbridge and Edenbridge.
Southeastern said extra services will operate between Hastings, in Sussex, and Tunbridge Wells and Ashford International and Paddock Wood, in Kent.
Some services from London to Kent will terminate at Sevenoaks.
Other services will be diverted upon departure from London to run via Maidstone East instead of Tonbridge.
Southeastern said all the changes are available on the National Rail app.