Primary objective of this forum post was just to alert you all that Metro replacement service 900 operates from today for two days (see below):

19th January - No trains Shiremoor to Whitley Bay
All day Saturday 19 and Sunday 20 January, to allow for modernisation work. Bus replacment service 900 will call at or close to all stations between Shiremoor and Whitley Bay. Please leave extra time for your journey.
Bus replacement stopping points
Saturday 19 bus replacement timetable
Sunday 20 bus replacement timetable


But also some Go North East diversions over the next couple of days too:


21st January - Routes 26 and 26A in Castletown
Castletown Way, Sunderland, will be closed for resurfacing between North Hylton Road and Wessington Way between 8am and 6pm from Monday 21 January for up to three days. Routes 26 & 26A are unable to serve North Hylton Road and Fern Avenue during these times, and will divert from Sunderland Road via Stoney Lane, Alexandra Avenue, Hylton Park Road, Timber Beach Road and Colima Avenue to Castletown, in both directions.

20th January - Routes 39 & 42 - Borough Road/Tavistock Place, Sunderland
Toward Road will be closed between Borough Road and Tavistock Place from 8am to 4pm (approximately) on Sunday 20 January 2013. The closure is required for works in connection with the Better Bus Improvement Programme.
Go North East services 39 and 42 will divert from Toward Road via Peel Street, Salem Road and Tatham Street to Borough Road, in both directions, omitting one stop (Toward Road – The Mowbray).


I'll hopefully be out on the go taking photos of the 39 and 42 on diversion tomorrow, and also I should get a photo of the Metro replacement 900 service too. Go North East are operating it today and I'd assume they were operating it tomorrow - but anything's possible!