From National Rail website:
Rail replacement bus services calling at all stations between New Cross Gate and West Croydon except Penge West but additionally at Crystal Palace and Selhurst are scheduled to operate in both directions as follows:
SATURDAY
From Forest Hill towards New Cross Gate every 10 minutes from 0535 to 0035 (5 minutes later from Honor Oak Park)
From Forest Hill towards West Croydon every 10 minutes from 0538 to 0008 then 0028, 0048 and 0108 (5 minutes earlier from Honor Oak Park)
From New Cross Gate towards Forest Hill every 10 minutes from 0525 to 2355 then 0015, 0035, 0055, and 0105
SUNDAY
From Forest Hill towards New Cross Gate: every 10 minutes from 0630 to 2350 (5 minutes later from Honor Oak Park)
From Forest Hill towards West Croydon every 10 minutes from 0658 to 0008 (5 minutes earlier from Honor Oak Park)
From New Cross Gate towards Forest Hill every 10 minutes from 0645 to 2355
BUS STOPS FOR REPLACEMENT BUS SERVICES
For stations towards New Cross Gate the buses will use Bus Stop E on Dartmouth Road (by Stanford Estates where 122 stops) and bus stop HB on Honor Oak Park
For stations towards West Croydon the buses will use bus stop B in London Road (by the Guava Kitchen) and bus stop HA on Honor Oak Park
From New Cross Gate the buses will use bus stop R in New Cross Road
ALTERNATIVE OPTIONS
Hopefully the traffic won’t be as bad as it was two weekends ago so the replacement buses will be more reliable, however some may prefer to consider using services from the following stations in the area that can be reached using regular bus routes
Catford Bridge
To London Bridge - 4 per hour Saturday / 2 per hour Sunday
To Cannon Street - 2 per hour Saturday & Sunday
To Charing Cross - 2 per hour Saturday / 0 direct Sunday but 2 per hour by changing at Lewisham
Catford, Crofton Park and Nunhead
To Elephant & Castle and Blackfriars (2 per hour on Saturday but no direct services on Sunday due engineering work. but replacement bus service from Catford & Crofton Park to Peckham Rye for London Bridge service.
Crystal Palace
To London Bridge via Tulse Hill 2 per hour Saturday & Sunday but takes 28 minutes on Saturday and 31 minutes on Sunday!
Peckham Rye
To London Bridge 4 per hour Saturday & Sunday
To Elephant & Castle and Blackfriars 2 per hour on Saturday but no direct services Sunday due engineering work
Penge East and Sydenham Hill
To Brixton and Victoria 2 per hour Saturday & Sunday