I know a bit about what is going on in relation to the NLL works. The
NLL closure was originally planned for 16 weeks starting after xmas,
however this has now been delayed until mid february. The reason for
the delay is that Network Rail have been unable to confirm closure
dates, as they do not have the required signalling software ready for
the new signalling between Camden and Stratford. If the route closes
in mid febraury (20th) then the route would repeon in early june (16
weeks). The closure will still be between Gospel Oak and Stratford.

During the closure replacement buses will run Stratford to Hampstead
Heath at 3 buses per hour. C Rd & Barnsbury won't be served. I would
imagine they will be a bit busy, so good luck trying to get on them at
Stratford in the morning! In addition the rail service will be reduced
Willesden to Gospel Oak from 6tph to 4tph. The trains terminating at
Gospel Oak will run at uneven headway so that trains for instance
arriving at gospel oak arrive at xx.10, xx30, xx40 and xx00.

Not sure why this isn't being made public yet. Although as people say
on here people like to know so that they can plan what they do.
Appears in this case to be a NR issue, but this doesn't excuse TfL not
keeping people informed. I expect their comms people are still trying
to work out how to put the River Thames back on the tube map, so don't
have time to worry about this!

There will be an xmas closure for 9 days over the xmas period on the
NLL for work to be done as well.