Rail passengers using the Brighton Main Line will face disruption over the bank holiday weekend from engineering work.
Gatwick passengers will be able to use alternative services from Blackfriars or London Bridge.
No services will operate between London Victoria and Brighton, but trains between the city and London Bridge will run in the early mornings and evenings.
On Sunday, buses will replace trains between Gillingham and Faversham, and between Sittingbourne and Sheerness in Kent.
Southeastern said rail replacement buses would also operate between Shepherdswell and Dover Priory on Monday.
Network Rail has advised passengers planning to travel over the three-day holiday weekend to check timetables.