Guys/Owd Nells.
It's right on the canal at Bilsborrow. It's about a 15 minute drive from my house so I go quite regularly. There is an italian restaurant (Guys) or a pub (Owd Nells). Both do excellent food, but it does get VERY busy at weekends, or anytime that the weather is nice, so it could be worthwhile booking a table.
http://www.guysthatchedhamlet.com/HOME/
There are lots of places to eat in Lancaster, though the Waterwitch which is right on the canal is nice.