LONDON, Nov 18 (Reuters) - British retailer Marks & Spencer (MKS.L) has struck a deal to sell some of its food products in Costa Coffee outlets, the companies said on Thursday. They said that from spring next year over 30 M&S food products, including sandwiches and salads, will be available in over 2,500 Costa Coffee stores across the United Kingdom as well as via drive-thru lanes. Costa, owned by Coca-Cola Co (KO.N), is Britain"s largest chain of coffee shops. M&S said the move supported its strategy to make the retailer "more relevant, more often for families". Last week, M&S beat forecasts for first-half profit and upgraded its earnings outlook for the second time this year, sending its stock soaring on bets that one of Britain"s most elusive turnarounds could finally materialise. read more Shares in M&S were up 2.1% at 0954 GMT, extending 2021 gains to 71%