Cladco in Rutherglen, Glasgow were fantastic with helping me get curved corrugated iron (steel ?) sheets for my pig arcs, they do all sorts of steel, straight, profiled, curved, flat etc etc etc and can fit no-con drop coatings to the sheets too.
http://www.cladco.uk.com/Ask to speak to Lewis Davie, tell him the mad wumin from Lesmahagow with the pigs recommended him and he'll sort you out
HTH
Karen x