I've never had a main credit card for about 20 years now that charges interest. Always transfer any remaining balance onto a new 0% card once the introductory period expires. Actually just did it a couple of months ago from a M&S Mastercard to a Barclaycard Visa with 0% on transfers and purchase for 18 months.Not if you have a decent length 0% introductory offer on the credit card
I keep an old Virgin Mastercard even though it's long past it's introductory period as it doesn't have any charges for using it overseas. Use it for emergencies only and always pay off the balance before any interest kicks in.