Urgent currency exchange question

[LaurelGrove]

Hi - if someone has Polish Zloty in cash and wants to change it to sterling, would they get a better rate doing it in Poland or here in the UK on arrival? If so, where? I'm tearing my hair out trying to advise a Ukrainian woman in Poland who's about to get on a plane to the UK tomorrow.

You'd need to look at the exchange rates here and there to compare

You would need to know both the exchange rate and the commission charged to make a comparison. Don't forget the rates change constantly so it will be a different rate anyway if she changes it on a different day (regardless of whether it's in the UK or Poland).
Is it a particularly large sum? If not I'd probably just go to Thomas Cook or nearest bureau de change- avoid the airport as they always have the worst rates/highest commissions

I can see how knowing the rates and commission would be helpful but just wondered if there was a rule of thumb that said it would usually be cheaper there than here (or vice versa). Will definitely tell her to avoid the airport.