Cheapest way to pay in London

We’re going on a short London holiday in january. We’re not british, so we only have french and dutch banks. I was wondering what is the cheapest way to get pounds. Getting money at an ATM costs 5% it seems. Should I get cash beforehand?

The cheapest way would be to get a British friend to sell you some pounds.

Maybe look at getting a prepaid debit/exchange currency card.

Use your bank card for everything. Everything. If you can’t, the idea of trading with a friend is a good one. There are lots of Brits in our village with whom I’m certain that I could cut a deal. ATM is last resort. Never use a local bank or currency exchange company. Outrageous rates…