October Train Travel - York

There's engineering works
https://www.nationalrail.co.uk/engineering-works/newark-18-oct-20261018/

LNER have yet to confirm how they are affected by these works.

This is just an educated guess on my part, but if you look at the web site, it's just some of the weekends that are (currently) blocked out. This could indicate planned engineering works. If you then check the LNER web site for changes to train times, it shows the weekends leading up to your planned travel as being used for major engineering works ( - no trains from Kings Cross, with LNER services starting from Peterborough and operating on a revised timetable. Buses from St Pancras to Peterborough. So I'm wondering whether they've blocked your date because they're not yet sure what sort of service will be running.

Someone else may have a better idea.

https://www.lner.co.uk/travel-information/changes-to-train-times/

[Edit, just seen's VAP's response]

I'll add that the OP can set up a ticket alert on LNER, and they'll receive a notice when or if London Kings Cross to York tickets are available. They might also look at something like traveling with East Midlands Railway from London St Pancras to Sheffield direct for £32 to £38 and then with Corss Country from Sheffield to York direct for £23.90.

Buses from St Pancras to Peterborough

That never happens on LNER due to London traffic. If the line turns out to be closed from Kings Cross the standard procedure is to divert passengers by East Midlands or Thameslink to Bedford, then bus from Bedford to Peterborough but IF the work is at Newark that won't work as Newark is north of Peterborough. The bus ride from Bedford is around 1 hour.

12 weeks is not cast in stone, often it can be around 8 to 10 weeks when major engineering work is happening.

In the past LNER have been able to run a limited train service diverted via Lincoln non stop between Peterborough and Doncaster. They will probably also run bus replacements between Peterborough and Doncaster express and all stations (1hr 45 express) . And if the work is at Newark trains will also run from London Kings Cross and St Pancras (the latter on Thameslink) to Peterborough.

Currently my usual self diversion route via Sheffield as above is sub optimal. East Midlands Trains are having a lot of problems with a shortage of fleet- therefore many cancelled and short formed trains, and no seat reservations. Standing even in first class is a frequent occurrence with 5 car trains running in lieu of 10 and a widened service interval.

We just have to wait patiently for timetable release, and see what service is being provided.

If I was self diverting I would probably choose Trans Pennine York to Manchester, and Avanti Manchester to London Euston under the current circumstances. Avanti also have delayed timetable release for that weekend- expected today (Wednesday).

However while Avanti have not released timetables or tickets for 18 October yet I can see that although trains are running from Manchester to Euston they are reduced from an every 20 minute frequency to being hourly.

EDIT- I've just had a sneak peek using Real Time Trains. I can confirm that some trains are running diverted York to London via Lincoln, others have the bus replacements Doncaster to Peterborough, then LNER (half hourly) and Great Northern (infrequent) trains Peterborough to Kings Cross, or Thameslink Peterborough to Kings Cross (diverted from St Pancras, hourly).

The diverted trains are-
York depart 0856, 0954, 1123, 1158, 1258, 1358, 1459, 1558. 1658, 1758, 1858, 1958 and 2105 for the 3 hour journey to Kings Cross.