Keswick is particularly well-supplied with pubs and restaurants, which serve a variety of mostly traditional food. Of the pubs, The Dog and Gun is a favourite (it also has free wi-fi), with beer from local craft brewery Keswick Brewery. You can also visit the brewery and have a guided tour and their brewery tap sells our own excellent cider. We also like the George Hotel for evening dinner.
If you like beer, or are just interested in how it is made, then the Jennings Brewery Tour, Cockermouth is strongly recommended.
For luxury dining, then The Cottage in the Wood along the Whinlatter pass is highly recommended, as is The Highfield Hotel & Restaurant in Keswick. The Pheasant Inn at the top of Bassenthwaite lake is also very good (with a choice of bistro or restaurant).