The Prelude by William Wordsworth — The autobiographical poem with whole books devoted to his Hawkshead childhood. Reading the school passages in the village where they happened is the obvious thing to do.
The Tale of Samuel Whiskers by Beatrix Potter — Set in Hill Top Farm itself; you can see the staircase in the kitchen and the cheese in the larder appear in the illustrations.
Beatrix Potter: A Life in Nature by Linda Lear — The standard modern biography, particularly good on her transformation from picture-book artist into Lake District sheep farmer and National Trust benefactor.
A Pair of Blue Eyes by Thomas Hardy — Set on the Cornish coast rather than the Lakes, but the only major Victorian novel by a writer who knew Hawkshead well enough to use it as inspiration for his characters' rural ways.