yes you can use expired film. in fact, the expiry date is actually the best time to use the film. the chemicals in film are sensitive to not only light, but heat and time. assuming the film has been stored under normal temperatures and it's not been exposed to light, then time is the only real remaining factor. obviously, consumer film is designed to sit on the shelf for some time (years), so manufacturers design film to be a bit 'raw' at first. it matures to its optimum age around the expiry date, afterwhich its performance starts to decline... every so slowly and slightly (basically unnoticeable). don't worry, consumer film that's a year or maybe two after expiry will work like new. no problem. higher end films, pro films are not designed to sit on shelves as long and come out of the factory right at their optimal 'age'. the reason why you see them in refrigerators is to keep them at that age. in fact, if you want, you can freeze film to keep it at a certain age indefintely. just make sure you thaw the film completely before opening the container, otherwise water will condense on the film or perhaps even crack.
GJ