RE: How costly is it to use a European credit card in UK? This is how much I paid to exchange Euros to Pounds.

This one should be relevant for personal use for a Austrian: https://www.revolut.com/en-AT/legal/standard-fees/

I use the card when I travel, and for wiring money to people from outside the Czech Republic.

I’ve never paid anything extra besides of that 0.5% for converting more than 1k euro, but even this happened just once or twice. My girlfriend has the app too, so we can exchange up to 2k with no fee.