The only problem we have had with Nationwide is that, before we left England, we were asked to give a maximum daily amount for withdrawal.
We opted , I think, for 280 euros, an amount which i soon forgot until I then tried to draw 400 euros. The machine then told me "insufficient funds" and retd the card.
When I tied again, it with a reduced amount, it was OK
So... Maybe check your max cash withdrawal.
Negg