Yes, yes, no… I don’t understand
If you’re afraid to come to New York for fear of your English not being sufficiently fluent (“It was a long time since I had a conversation in English, no one will understand me”), I have some advice: forget the fear. What’s more: the less you try to speak correctly – the way you were taught by your mostly British teachers – the better off you are. Straining yourself to be grammatically correct (“Should I use past simple or present perfect?”) and to pronounce your sentences like you were Queen Elizabeth II herself, will only make you feel more stressed out. Most likely, no one will even understand you. This place is full of people from all over the world, including places that never heard spoken English. You will hear every language there is, as well as every dialect – starting with African languages, Hindi and Chinese, and – when you least expect it – Polish, Russian and the ubiquitous Spanish. Sometimes it will happen that not a single one of your fellow subway commuters will speak English. And none of them will be even a tourist that you are.
It’s often the case that even the immigrants who have lived here for 2, 4 or as much as 10 years don’t know English – which is true for many Poles, too. The truth is that most of them don’t need English to function over here. Transport and getting around are easy in NY; you don’t need to speak any language to do that. Besides, many immigrants live in ethnic-specific neighborhoods among their compatriots, who all speak their native language (same goes for store clerks). All you need is to master some basic phrases you need at work and a couple of indispensable words. That’s why so many foreigners have trouble learning the language properly, and even when they try to use it is often in a simple, rudimentary way (with the present tense serving to describe both past and future) and with no specific accent to speak of – everyone imposes their national accent upon their English.
Things will look much differently, of course, if you end up working for American companies with American colleagues – in everyday life, though, you can get by very easily. All you need to get your message across in a store (or a café, or on a street) are basic phrases, and if they don’t work, you should just smile and narrow your vocabulary down to “yes” or “no”. If you don’t understand something, just widen your smile and say it outright: “I don’t understand”. You can always use body language, too, and simply show what you mean with gestures. If you run across a person who speaks as little English as you do, then (even if you won’t have much of a conversation) at least you will get to smile a lot at each other and finish by wishing each other a nice day (by uttering one of the most useful phrases in American English).