Chick Lit book about a ghost who is in love with his best friend who works in a cafe, help please?

Its driving me crazy, the book was an english chick lit type about a boy and a girl working in a greasy spoon cafe, and the male dies after falling into a canal. He always had a crush on her, but never told her how he felt. As a ghost he follows her to try and make her see him, she is in a bad relationship.

Im sure the book is set in London and he leaves her a KitKat at one point.

Very vague, I know, but its a long shot!

Help!! xxxx