piqla,
You said earlier "i'm not a polish guy (but i'm from Eastern-Europe), and from what i've heard the English people don't like them too much and maybe they will think (do you?) that eastern-european is eastern-european..."
Have you ever been to the UK? If you haven't, maybe it's worth spending some time here before you apply to NATS. After all, if you're successful, you'll be here for rather a long time...