Real Estate / Mortgages for apartments in Poland - what currency? [9]

I get paid in Sterling .

I got a quote from PKO bank as they now have branch in London as well which makes things easy

Ex a £50,000 mortgage in £ = interest rate of 8.3% = monthly cost 1873 PLN

50k taken out in PLN = IR of 7.13% monthly rate = 1647 PLN

but in Euro rate was 4.68 % & 1371 PLN / month

so Euro would seem cheapest !!!!!

You thoughts please