As can be seen from the route map below, the Northumberland Coast Loop wouldn’t directly serve Ashington, with it being on a branch from the main route between Newcastle and Berwick.

This is perhaps most clearly seen on the geographical map from Rail Map Online below, where after leaving the main route at Bedlington, the line continues through Ashington to Lynemouth, with the Cambois Branch also diverging near Bomarsund.
The line near to Linton Colliery, north of Ashington (known locally as the Butterwell Line) is beyond the scope of this post, as the connection to Ashington has been out of use since 1999, and has never formed a northbound link, only a southbound one.

While Ashington wouldn’t therefore be a stop en-route, the Northumberland Coast Loop could though still hold advantages for Ashington in reducing journey times to and from the North of Northumberland.
Bedlington, Blyth Bebside or Pegswood for Ashington
While not served direct, Ashington would be within easy reach of Bedlington or Blyth Bebside stations, being just one or two stops away respectively, offering a very short and reasonable connection by rail; shorter than connection via Newcastle Central in both time and distance.
Another option would be travelling via Pegswood Station, which would offer interchange with local buses (No. 35 particularly), but ideally the simple addition of a car park could upgrade this modest station into a ‘Pegswood Parkway’, easily accessed from many areas by its strategic location on the A197, linking the A1, A697, A1068 and A189 roads.
Blyth Bebside in particular would probably be ideally suited to the role of a local hub, with easy connections being possible by rail, bus and by car (as it is being built with a substantial car park from outset), whereas Pegswood would require the addition of a car park to form a potential ‘Pegswood Parkway’, and offer similar ease of use to Blyth Bebside.
All of these options could allow for easier access both to and from Ashington for access to work, education or training, especially from North Northumberland where existing connections are somewhat awkward.