Not sure if Overground is working BTW; or if there are rail replacement buses:
"All day on Sunday, no Southern trains will run to/from London Bridge. There will also be a reduced Thameslink service between Bedford and Three Bridges.
A limited Southern service will operate between South Bermondsey and Caterham via East Croydon. Please connect at Purley for Tattenham Corner trains
- Customers should use Thameslink services to trvel between London Bridge and East Croydon.
- For journeys between New Cross Gate and London Bridge, please use London Overground services yo Canada Water and Jubilee line services to London Bridge.
- For local journeys between New Cross Gate and Norwood Junction, Southern tickets will also be valid on London Overground services which are not affected by these works.
- Thameslink services between London Bridge and Horsham will also call additionally at Earlswood and Salfords.
This work is required to repair a key set of points just outside the side of station used by Southern. This work is essential to avoid a speed restriction being imposed.
These changes are now shown correctly in the National Rail Enquiries real-time Journey Planner."