been offered some 14 inch 4 stud fiesta wheels for my build ..would they fit Cortina /sierra 4 stud hubs.dont want to buy them if they wont fit...

I could give you 2 wheels that will fit. I work in Chesterfield so could meet up

Only difference may be the offset, ford fwd offset is usually higher. shouldnt cause issues for build wheels unless the are tiny wheels, as the higher offset may limit suspension and caliper clearances.