Sfumato refers to a painting technique where there is a gradual transition of colors which creates the impression of soft tones throughout the canvas.
A shandy is a a working class drink composed of lemonade and beer.
Butcher's Hook, or look, as in take a Butcher's is part of Cockney Rhyming Slang or Thief's Cant.
Chav is UK slang for a member of the Lower Classes. Actually Chav is a derogatory term for a young person of a type characterized by brash and loutish behaviour (usually with connotations of a low social status). Allegedly it originally formed from the acronym C.H.A.V, which was "Council House and Violent". They would usually be sporting branded tracksuits, branded trainers/sneakers such as expensive Nike, and baseball caps, An American equivalent phrase could be "gang banger", or the American definition of "punk".
A toff is UK slang for a member of the Upper Class.