Often, when travelling abroad, I'm asked whether I wish to pay for my products in the local currency or in GBPs. I also just placed an internet order where I was asked if I prefered to pay in US $ or GBPs. Does it make a difference which I choose? Thanks!
Indeed it does, you should always choose to pay in the local currency, this way the exchange rate charged is decided by your bank as opposed to whatever the seller wants to charge. At the very least you should find out what you will be charged in sterling and calculate what rate they are using. An article from 2005 but still valid http://www.guardian.co.uk/money/2005/dec/17/mo neysupplement2