If you do a one-off trip to somewhere and buy a ton of their banknotes you have the issue of the excess when you get home. You can sell them back but your supplier gives you a rotten buyback rate. As our hols are always in Europe, having euros left over isn't an issue. Caxton will convert them back for you, but they offer a rotten rate buyback rate too. You could consider getting a traveller's card that lets you draw out currency from ATMs fee-free. They do exist! It's a bit off-topic is this, so later on I'll look up what Which? sez (I'm a member) and tell you what they recommend. One advantage of a pre-load card is that you can load up currency to it in dribs and drabs from your bank account while you're on your trip (if you can bring yourself to trusting the system!), so you don't end up with too much leftover mickeymouse dosh...