Planned engineering works will affect services running between Sutton and Wimbledon, with no services running between them on these days.
Engineering works between Herne Hill and Tulse Hill will close some lines, affecting Thameslink services between Herne Hill and Sutton, and Herne Hill and Wimbledon.
Amended services will run between New Cross Gate and Crystal Palace, impacting Thameslink services between London Bridge and Horsham and Brighton.