Peacocks/Primark in the uk?
Unfortunately not. I know a few Polish people who go to Berlin or even a cheap flight to Doncaster Airport and come back loaded with Primark stuff.
As for the language, don't get stressed by grammar tables, just speak and don't be afraid of making mistakes. Poles make mistakes when they're learning English, and so will you when you're learning Polish. Peter_Olsztyn's advice is good. I'd add that childrens' TV is a good way to start, and keep your eyes open for what is around you, shop signs, adverts etc.