Market traders and ice cream vendors don't often take credit cards. Cash is King!!You mention phone card does your current sim provider not have roaming? Three lets you phone a phone number in the country you are in or a UK number for free. There's always what's app or similar ... As to currency we don't bother and use a credit card - Halifax Clarity or one that doesn't charge for foreign transactions. PS are you planning on going off piste into Germany?