Hi Tooomek,
As long as you meet the entry guidelines and have the right to live and work in the UK for an unrestricted amount of time you shouldn't face any trouble with being chucked out because you're Polish. If anything, it may help you! NATS are very keen to employ people from other areas outside the UK, especially people of different cultures and faiths (assuming you pass S1,2 and 3).
If it's your English you're worried about, well, you write better English than posters here who have lived in the UK their whole lives!
Good luck, let us know how you do.
Not too sure about your S1 enquiry but I'm sure someone else will be able to help you out.
S88