https://www.northernrailway.co.uk/newspaper-offer
The above link gives details of the usual £10 day and £17.50 weekend Northern all line ticket offers.
The offers run from 20 Jan 2020 to 22 March 2020 although availability of the newspaper tokens is limited to a 2 to 3 week period from 20th Jan 2020.
JPIMedia (Jonson Press) & Reach PLC newspapers are the participants, for more details visit the link above.