There's a large middle eastern supermarket in Slough. I forget the name of it but it's at the end of the High St, opposite Nandos. Great for food from Turkey, Cyprus, N. Africa, Iran, Saudi, Lebanon, Egypt etc etc. Lots of specialist ingredients plus fresh fruit, veg & herbs, patisserie counter, some kind of bread (I didn't check what kind) made right in front of you and a take away pizza counter! And almost an entire aisle dedicated to pickles!