My advice would be to get a no international fee credit card.
There are a few options out there, like Halifax, but I’ve already got one of their balance transfer cards so that was ruled out. This meant I ended up with an Aqua card.
HORRIBLE interest rate, but just pay it off each time. Also stingy on the first credit limit it gives you, but fill it and pay it off and it quickly doubles and doubles. You can easily over pay it to begin with, or top up on their online banking if you’re going to be spending loads.
http://www.aquacard.co.uk/credit-cards/aqua-reward/
The whole point? No fees and uses very standard exchange rates. I’ve used it all over the world and it’s golden.
Just remember to pay in the local currency so you’re using your own exchange rate as some hotel/shop ones can be a little enthusiastic.
The ability to chip and pin a coffee on a airport transfer knowing it’s UK debit card style cost price is worth it alone!