I would assume you are supposed to use the tube from London Bridge or maybe Blackfriars. Victoria could be dodgy.
Through tickets will be valid on the routes shown
Thameslink route: All day, no trains will operate through central London
13 Apr 2013
In detail
All day, no trains will operate through central London between West Hampstead Thameslink or St Pancras International and Blackfriars or London Bridge. Through tickets will be valid on the routes shown. Farringdon station is planned to be closed.
Bedford route: All day, up to 4 trains per hour will operate between West Hampstead and Bedford calling at St Albans and all stations to/from Bedford and vice versa. Up to 2 trains per hour between Bedford and West Hampstead Thameslink will extend to/from St Pancras International. Journey times on these services between West Hampstead Thameslink and St Pancras International will be extended by up to 15 minutes.
Up to 2 trains per hour will also operate in both directions between West Hampstead Thameslink and Luton calling at all stations. Trains will be unable to call at Kentish Town. Replacement buses will operate between St Pancras International and West Hampstead Thameslink calling at Kentish Town.
Brighton route: All day, up to 4 trains per hour will operate in both directions between London Bridge and Brighton to an amended timetable. Late night services will operate between London Bridge and Three Bridges.
Sutton route: All day, up to 2 trains per hour will operate in both directions between Blacfriars and Sutton via Mitcham Junction. Up to 2 trains per hour will also operate in both directions between Blackfriars and Sutton via Wimbledon.
Why
Planned engineering work.
When Capital Connect services are not running between St Pancakes and the Bridge, London Undergound accepts tickets for entry/exit at West Hampstead, Kentish Town, King's Cross St Pancras, Farringdon, Blackfriars, Elephant/Castle and London Bridge stations only.
This is logical. Its worth reminding that other forum users have been in hot water for using an FCC ticket at Victoria (doubtless someone can link to it).
When Capital Connect services are not running between St Pancakes and the Bridge, London Undergound accepts tickets for entry/exit at West Hampstead, Kentish Town, King's Cross St Pancras, Farringdon, Blackfriars, Elephant/Castle and London Bridge stations only.
When the core is closed, FCC tickets are usually valid on the 17, 45 and 63 buses, with dedicated rail replacement buses running overnight if you can find them.
Just found this (I'll be travelling via 'Thameslink' on Sunday now)
The document for St Pancras International on this page of FCC's website suggests that FCC tickets will be accepted by London Underground and Southeastern - recommended route to some destinations (e.g. Herne Hill) includes travel via Victoria.
Unless 'disruption' in this context means emergencies, not planned engineering work...
The norm for core closures is to travel via the northern line from st pancras to London bridge. What your reading is for service disruption I.e wires down, points failure etc etc.
http://www.firstcapitalconnect.co.u...nned-timetables-changes/details/TL2013-04-14/
... and in practice at St Pauls, although I can only speak for disruption, rather than planned weekend closure.
Just found this (I'll be travelling via 'Thameslink' on Sunday now)
The document for St Pancras International on this page of FCC's website suggests that FCC tickets will be accepted by London Underground and Southeastern - recommended route to some destinations (e.g. Herne Hill) includes travel via Victoria.
Unless 'disruption' in this context means emergencies, not planned engineering work...
It isn't listed as acceptable in staff bulletins for the weekend engineering works, but would possibly make sense given the proximity of City Thameslink (at least on Saturdays).