POST SUCCESSFUL TRIP UPDATE:
I had carried an HDFC Regalia Forex Plus card. You can load money in US Dollars to it and swipe it anywhere, in any currency. The conversion charges will only be applied when loading money, not while using it. ATM withdrawal costs $4 per transaction. My previous card (the one in my original question content) charged $2 per withdrawal but it would cost me double conversion charges. As I mentioned in the description, it had 23 currencies but it didn't support Zloty, so I would be charged twice, once for loading money, depending on the currency I load, and then for conversion from that currency to Zloty. It could be any other country who's currency is not supported by this card. The ATM withdrawal charges are irrespective of the amount you withdraw.
I had a successful trip, and didn't need to withdraw any cash, any time. My Forex contactless card was accepted everywhere. I mean literally everywhere, including the machines inside trams, trains, restaurants, even small stores. I haven't even seen the Polish currency! :) I used the same card in UK and Germany, and most of the times didn't need any cash. In my entire trip, I withdrew money only twice. Once in Derby to pay my Airbnb, and once in Itzehoe (Germany), to pay my taxi driver.
So anyone who stumbles across this post, don't worry about cash or not in Poland, UK or Germany. It's safe to withdraw a sufficient amount once and store it somewhere as a back up. Contactless works in most of the places.