i think what helps our shopping bill is buying frozen veges and eating typically 'english' filling meals. so we don't snack on anything apart from toast really.
I throw tons away and I probably only buy sone things through laziness! Although I don't think I'd save much not buying those things . I cook alot for friends on a Saturday evening, the last lot cost me £60 not incising booze, I need shares in sainsburys!