Several retailers, including Britain's biggest supermarket group Tesco TSCO.L and online fashion seller ASOS ASOS.L, have warned about the profit outlook this month as they face higher energy and staff costs, and a weak pound. Adds details and background LONDON, Oct 21 (Reuters) - British retail sales volumes fell by a bigger-than-expected 1.4% in monthly terms in September, official data showed on Friday, as consumers felt the hit from rising prices. A survey published overnight showed consumer confidence remained close to a record low as households responded to the combination of high inflation and Britain's chaotic politics.