soph, nope the checkout staff arent on rolling contract(they were on normal contracts as the rest of teh staff in the store), i know from experience as i usedf to work for Mr S, any job vacancies are advertised on the internet these days, you can try going to the stores but they may say to check the website(we didnt actually know what if any jobs were available for our store). As well as the supermarkets theres also other retailers who have checkout staff eg argos, comet, currys, pc world, staples, bhs, marks and sparks, debenhams, dunelm, wh smiths, john lewis,
i went off on a tangent there, were you specifically wanting checkout work in a supermarket ?