Saw a notice at the station this morning saying no northbound trains this weekend. Tried looking online for more details but it doesn't make much sense:

Southern's version
Network Rail's version

According to Network Rail's online timetable (which takes engineering works into account) you can go south to Norwood Junction and take a fast train to LB. The LB to Victoria service will start at Crystal Palace, so no FH to Victoria trains (and therefore fewer LB to FH trains).

Has anyone ever heard a recorded announcement at FH station advising passengers of weekend engineering works and referring them to station notices for details? The Forest Hill Society suggested to Southern that such an announcement would be useful and the reply was that there already was one. Can't say I've ever heard it.