The revised Waterloo South Western Railway timetable from December 2018 is predicated on the reopening of the old Eurostar International platforms – see HERE.
The work to bring those platforms into use has been part of my regular Waterloo Station photo reports of the ongoing work – see HERE for all the articles in descending date order.
My most recent article – HERE – surmised that the engineering works would not complete by December. I’ve not been to Waterloo station since. Therefore I’m relying on comments in the Back to the Future: (Re)lengthening and Shortening at Waterloo article in London Reconnections website.
These comments, the latest on December 11th, indicate that platforms 19, 20, 21, and 22 are in use, and that the new walkway is open, although there is ongoing work in the ‘orchestra pit’. My most recent photo opposite – click to expand..
Meanwhile, again reading in the superb London Reconnections website that the revised time table for additional, and longer trains will not apply before May 2019. There’ not mention of this fact in Network Rail websites that I can see. Apparently there is insufficent power to operate the trains. The situation is fully explained in A Good Spark is Getting Hard to Find: SWR and the December Timetable.