How much notice do you have to give?
buy abana EU regulations make it clear that, when a flight with an EU airline or from an EU airport is cancelled, an airline is liable to pay for the cost of a hotel and subsistence for all those stranded as a result, until a replacement flight is provided. Should your airline advise you to buy your own food and accommodation, keep all receipts, and keep such costs to a reasonable minimum, before making a claim when you get back to Britain.