Mattress pads are not normally used for mattress protection as they tend to be around 5-7cm in depth and particularly, in terms of a pillow top, they would remove the feeling provided by that top. What we would advise is a good quality cotton mattress protector, which can be purchased from a number of high street retailers. These are typically quite thin and still allow you to feel the soft comfort provided by the pillow top. There is an article here on mattress care, which you may find useful.
If you have any further questions please don’t hesitate to contact the office on 0161 437 4419