Or for foreign currency get yourself a Santander Zero credit card. The Zero in the title is the important bit - zero fees, none at all. Withdraw cash from an ATM abroad and there are no fees; no cash withdrawal/advance fee, no FX loading, no transaction charge at all. You get wholesale bank-to-bank spot, the rate at which Mastercard settle their net FX position at the end of the day so, at worst it’s the wholesale bid price but sometimes (GBP/USD almost always) you’ll get the offer rate, even better than mid-market!
Only downside is the interest rate (I think 30% ish?) chargeable from the date of withdrawal but that’s easily avoidable - either immediately credit your account same day with on-line banking or, in my case, I just pre-load it, keep a mental note of what I’ve withdrawn and top it up as necessary. Any excess when I get back to Blighty I can simply withdraw here (no cash advance fee) or simply run it down with purchases. Oh and there are no ‘rewards’ but that’s a very small price to pay.
In the US it’s slightly harder as most banks charge you for using their ATMs unless you are a customer so that fee (not levied by Santander) is unavoidable unless you can find a Santander branch or affiliate - Sovereign Bank in NYC and some other places.
Seriously, people don’t believe it because it sounds too good to be true but, for once, it actually is true.
Not sure whether there are any restrictions on who can have a Zero card.
ITDYA, thinking there used to be a Halifax card, Clarity I think that was similar but they didn’t allow you to pre-load - they can’t actually stop you just I’ve have heard rumours of them cancelling the account when people did. No idea whether true or no but what I heard.