Credit cards work just about anywhere, but we always carried cash also. Just go to the local ATM, they are everywhere including at airports and train stations. In fact the first thing we did when arriving in each country was to get a couple hundred dollars in the local currency for our week there.I wore a money belt for passports, Eurostar tickets and extra credit cards, but carried all the local currency in my wallet that I always keep in my front pocket. Things in England seemed much more expensive than France because the exchange rate was about $1.88 per pound and in France it was about $1.30 per Euro. Check the current exchange rates using a Currency Converter.