AM peak will have 6 tph Morden - Charing Cross with 2 tph fewer to Bank (24 rather than 26 trains in the busiest hour). Through the off peak the 6 tph Morden - Charing Cross continues with 24 tph total to Morden, but with 18 tph everywhere else bar Mill Hill East rather than the normal 20 tph. The PM Peak is mostly as WTT57 (6 tph Charing Cross - Morden already). Weekends mostly as per off peak, Night Tube as normal.
Improvement works being, turning the station in to another bathroom with passages that add on an extra 5 minutes of walking to the interchange?
I can’t see any need to mess around with the tiling beyond making good any areas directly affected by the works. All that’s happening is a few extra cross-passages — the only reason for the closure is that the City platforms are too narrow to do the work with passengers still using them, a legacy of the C&SLR. The work is also complicated because these two platforms happen to be two out of only eight surviving brick Tube platforms, another CSLR legacy.