I did it from Morpeth to Wooler in April, and enjoyed it. There's some lovely views across the Northumberland National Park, thought it was numbered X16 though.
It is the X16, those journeys being an extension of that service which just runs between Newcastle & Morpeth the vast majority of the time alongside the X14/X15/X18 although the X16 additionally serves Stannington (village northbound, sliproad southbound).
Looking to have a go of the Saturday only 419 that runs in a loop via Belsay, Wallington and Scots Gap to/from Morpeth, it's possible to catch the first X75 from Newcastle to Wallington and change to the 419 to Morpeth there. Also on Saturdays, there's the 415 Morpeth to Alnwick via Swarland and 460 circular via Ellingham to/from Alnwick.