Screws for rad and fan?

Could anyone tell me where I can find a set of screws for fitting a 120mm YS-tech onto a Maxxpert Mono rad in the UK?? Have been around all the major hardware shops, and nobody seems to sell screws that are long and thin enough

buy #4 all thread, (AKA threaded rod) and some nuts. that's what almost everyone uses when they can't find the correct sized screws/bolts.