Chebby; if you live near a Wilkinsons you should be fine (other retailers are avaliable).
Wilkos stock a fair few Astonish products. They're very good; we (wilkos) use their cookware cleaner to clean shelving etc.
To my knowledge, a 'closed cell foam pad' is basically a magic eraser (http://en.wikipedia.org/wiki/Melamine_foam), which is very soft at a macro level, but has hard edges at the micro level.
Interestingly, some websites recommend (I haven't summoned up the courage / stupidity to try this yet) magic erasers as stylus cleaners, where by the stylus is just lowered onto the foam, or a very small section is moved in a linear fashion front to back.
I'm a little sceptical about that, but their cleaning power is undisputed.