Take some cash with you when you travel abroad for places that don’t accept plastic like small shops, taxi’s etc. Cash machines do not give you the best rate for changing money, you will get a better rate if you exchange cash at a foreign exchange.
To change money there are a variety of options. I find that Marks & Spencer’s, Travelex and the Post Office are all a rip off. The worst foreign currency exchanges are the ones in the airport which have huge ‘margins’ (the difference between what they buy a currency from you and what they sell it to you).
Never pay commission, but just because they are advertising 0% commission doesn’t make their rate any good. Check online, I check Yahoo Finance. Then you want to get the closest rate to this that you can.
Thomas Global exchange which has 4 branches in london.
In general go to the little hole in the wall places with one guy cooped up in his little glass prison cell and he will have better rates than the high street banks, stores and even the chain currency places. Competition is good!
Better yet, exchange money directly with your friends. Just look online and get the rate at that time for the currency you have from Yahoo Finance and calculate it.