@Sloopy .Dog - welcome to the group.
I have never heard anyone say that the garage buildings were once owned by the National Coal Board (NC) but I will ask around and see what I can find out. I will also ask around about a 'small chapel'. I have never know there to be a chapel in that area - I no longer live in Bedlington. I was born, 1948, and raised there , but I can't recall a small chapel in that area you have mentioned.
There were two coal mines in Bedlington. The 'A' Pit (used to be Sleekburn Colliery) and the Doctor Pit. The 'A' pit was where the Bower Grange Estate, Bedlington Station was and the Doctor Pit was at the Top End of Bedlington and Gallagher Park now covers a) where the Doctor pit buildings b) where the branch railway line connecting the 'A' pit & the Doctor Pi and c) where the 'pit heap' shared by both pits used to be.
Later I will post you some links to info on the pits and some photos of the pits .
Could you tell me exactly where the small chapel is - this is a current ectract from Google Street View showing Ravensworth Street and area :-