Found this on service status page, covering coventry:
On the morning of Wednesday the 23rd of November between midnight and 6 AM,
Network optimisation will result in a loss of service in Colchester, Wardley, Shepshed, Ashton, Wearside, Waltham Park, Cheshunt, Mansfield, Bishopbriggs, Coventry and the surrounding areas.
On the morning of Thursday the 24th of November between midnight and 6 AM,
Network optimisation will result in a loss of service in Wardley, Shepshed, Cambridge, Belfast, Baguley, Brighton, Cheshunt, Mansfield, Hartlepool, Clifton, Grimsby, Northampton, Canniesburn, Coventry and the surrounding areas.
All still listed as ongoing, so the dates don't seem to indicate when the work will be completed, sorry
