This used to be my commute!
Directions as Ton’s post. Watch out for glass on the bit leaving Selby after the bridge.
Get through Barlby, bear left at the other end of the village to go down past the new housing estate, then along the side of the A19 (on separate cycle path though) to Riccall. Through the village, bear left at the other end of that village and you’ll pick up the cycle path proper.
There’s an honesty hut thing at Naburn thats usually open in the summer (never used it). Or there’s a co-op etc in Bishopthorpe for ice cream.
Its a really nice ride once past Riccall.
Email is in profile if you need any help etc. we live in York now and happy to fill bottles etc if we’re around.
edit: oh and ‘pretty much flat’ doesn’t do it justice! Its the old railway line, and i’m not sure it could be any flatter!