I have just had a look through the Engineering Access Statement for 2020. The only date in 2020 which may affect Barton Line trains is Sunday 11th October if we have the year round Sunday service by then.
TPE services to Cleethorpes will be affected on the following dates:
Replacement buses between Scunthorpe and Cleethorpes:
Saturday 11th January 2020 (from 23:00)
Sunday 12th January 2020
Saturday 18th January 2020 (from 23:00)
Sunday 19th January 2020
Saturday 25th January 2020 (from 23:00)
Sunday 26th January 2020
Saturday 10th October 2020 (from 23:00)
Sunday 11th October 2020
Replacement buses between Doncaster and Sheffield
Saturday 21st March 2020
Sunday 22nd March 2020
It is pleasing to note that Network Rail aren't planning any summer tourist season disruption to Cleethorpes during 2020.
Replacement timetable 20th/21st July 2019
https://d2cf7kiw5xizhy.cloudfront.net/images/timetables/2019-07/week-17/N31_e1701a.pdf
Replacement timetable 27th/28 July 2019
https://d2cf7kiw5xizhy.cloudfront.net/images/timetables/2019-07/week-17/N31_e1801a.pdf
Note that on all affected dates, the replacement buses will not stop at New Clee, Grimsby Docks or Thornton Abbey. On the Saturdays, the 21:04 Cleethorpes - Barton rail replacement bus service will stop additionally at Ulceby.
From this coming weekend, we should see the return of Barton Line Saturday evening and Sunday train services. Sunday services run up to and including Sunday 8th September 2019. There are no more Barton Line engineering works in the pipeline.