When we stay in Grasmere we usually walk over the hill to Elterwater for lunch at the Britannia Inn.
Have gone over for an evening meal a few times. Very friendly place. Nothing fancy at all and if you have a dog or two they are very welcome as well.
We love the Lake District and have a timeshare lodge on the Langdale Estate, the Britannia Inn is a few minutes walk away and gets another vote from me. SWMBO is French and always thought that English food was rubbish, seven years after her first visit to the Britannia she still raves about the food there and sites it as an example of how good English pub food can be.
We'll be up there in August, can't wait.