When Arriva replaced Ashington Depot a few years back, they should've either built a new depot in either Bedlington or Cambois then merged both Blyth & Ashington into 1x depot with the Alnwick & Berwick routes run from an outstation in Alnwick.

I think Cramlington would be a good middle ground for a new depot. Sandy Lane would have too much dead mileage for the Blyth routes but Jesmond do have a few outbound route starting points nearby Cramlington including Cramlington itself that would make it ideal.