Again conflicting advice as we put slate down as we'd read it was a good substrate yet when we told the man in the shop this he said he'd never heard of it! Will stick with our original plan then as sounds like the sand is doing no one any favours!! Hadn't thought of the bran, can't really remove that one totally? Will start with getting rid of the sand and let you know.
Thanks for the advice guys, much appreciated as we're new to this