Shoppers have been warned that they may be paying more for everyday items at supermarket convenience stores than they would at their bigger counterparts. Consumer champion Which? said: “We checked the cost of 42 branded and own-label products – from cheese and pasta to blueberries and ice cream – on three occasions in June and July.” Doing your shopping at a large supermarket as opposed to a convenience store could save you hundreds of pounds per year. The Which? team found that a grocery shop at Tesco Express set them back £10 (11 per cent) more than the same shop at Tesco supermarkets for lo…