Scottish I'm guessing hence the "aye
Scots are not the only Brits who use the word.
Insurance: At the very least, you should have one of those little blue European Health Insurance Cards.
If you're on a work contract, you'll need a residence permit. If you're working legally, you'll need to pay ZUS (Polish health insurance).
As I said, check out old threads on the forum. You'll find a lot of detailed, relevant and true information by people who know what they're talking about.