NickH

You will struggle to make a decent job of the fall by building up with adhesive, amongst other problems you will end up too high for the rest of the floor, the floor should drop DOWN to the drain either by building a slope into the floor or by using a flush fitting preformed "former", such as an Impey Aquadec. Impey also do a tanking system called Tilesafe which is good. Be very cautious about a wet room and dont do anything you're not 100% sure about. Get it wrong and you're in big trouble.