That got me thinking!
I had a quick look how atrocious Polish banks are and I was amazed. I thought that Barclay’s offer was ridiculous, but Polish situation is even worse. Some fairly believable article pointed that some currency exchange fees on holidays are reaching as high as 11%, which is made up of usual currency exchange fee + other fees, using poor exchange rates on top of that. And usually there’s ATM fee outside of Poland too.
If Monzo could offer no more than 3% fees all together and free ATM withdrawals, not to mention make it free 
, it would be absolutely loved in Poland.
Poland seems to be quite hip regarding banking approaches all together. It was only I moved to UK, when I learned that not many banks (if any, actually), require one-time password verification sent via text to your mobile, when you make online payments/set up regular payments/etc. When I got barclay’s pinsentry thing, my face was literally in 
shape. When I learned about 3d secure with one password repeated over and over again, I gave up. 
So, yeah, drop Monzo to Poland. All you need to do is explain why it’s cheaper than Polish banks - especially when thinking about holidays abroad. 