If the OP lives in London or the EU maybe he should look at the Revolut card. You can put pounds, dollars, and euros plus some other currencies. They exchange at the best bank rate with no markup I had one, but since I was living in the states they stopped closed all our accounts. I would carry Pounds and Euros on the card. It was nice to go somewhere to eat or buy something without worrying about DCC or exchange rate. You can order the card through the app. I have no affiliation except I wish they would hurry up and bring it back to the US.