I was thinking I could put in a tax claim each year as you're supposed to. So I would still be committing tax evasion?
Now...that's an interesting point. If you were paid through a UK limited company and were receiving nothing but dividends from the company (which you'd be free to pay as you want, I think?), you could just pay tax on the dividend income and have no liability for ZUS. As far as I remeber, dividend income is a flat 19% - and you wouldn't be paying any tax in the UK.
I think if you were self employed in the UK and yet residing in Poland, they'd have you with the lack of paying ZUS. But if you're simply the 100% shareholder and director of a limited company in the UK, as long as the company pays UK taxes and you tell the Polish taxman that you earnt x amount in dividend income, there shouldn't be an issue - I think.
Might be worth finding a friendly English speaking accountant and see what they advise?