Hi, Yes there are, in my city I can find a few (really few!) products in the supermarket indeed and there's even a small brit/us/can shop. They sell some Marmite, Haggis, shortbreads, the Million Dollar chocolate bar... yes that's nice. Some time ago I already used a shop online which does shopping at Tesco and Sainsbury's, and I was really happy with this service too.
But sometimes I want something more special, some 'gourmet' chocolate bars, not sold in supermarkets. Sometimes the manufacturers sale their products online, but you always have a really pricey minimum shipping rate, even for just one bar.
If I could find another chocolate lover living in London for example, when he/she goes shopping here and there from time to time, he could get his/her hands on a a select product, and when he/she got a few after two or three months then he/she can ship them together at once.