Yes - ask for cornflour. DO NOT use cornflour - totally the wrong thing.
eta: Cornflour in the UK is corn starch. This isn't the same as cornmeal! Still trying to find cornmeal in the UK, will add more when I know.
coarse cornmeal, polenta or maize meal or the more finely ground maize flour should be available in most big supermarkets often called - cornmeal, maize meal, maize flour, polenta, or polenta flour.