A. The best way to keep soap scum marks at bay is to wipe the bath every time you use it using a sponge and warm water; however, for more heavily soiled areas, use a good bathroom cleaning product.
Cillit Bang Grime and Lime is good for removing tough soap scum marks, but always check the usage instructions before use and test in a small area before proceeding, particularly if you have an enamel bath tub, as many cleaning products may not be suitable.