Do you think that English living and working in Poland speak Polish better than Poles living and working in England speaks English ?
If a firm in Poland wanted people to put coats on hangers and hang them on a rail,but these people must speak fluent Romanian(which they know is very unlikely) you would be rightfully appalled.It is a blatant discrimination against the local people and just fits inside the law on advertising.
Thats happening here now and if you are a reasonable person you will concede this point.
Migrants are entitled to free language tuition in the U.K so there is no excuse not to learn.
I and many other people in Poland had no such luxury.That said we all learned your language in order to live effectively and we put much more effort into doing it too.At the time I had great difficulty in finding a polish book/cassette to learn with.It was and still is a minor language.English is one of the two main world languages.Books are and always were readily available almost anywhere.Not many Brits will live all year round in Poland,but most of them will learn Polish and many will have a connection or special interest there.
As for which language is spoken at work.. Thats the firms choice but i would say that people must be able to use english when its neccessary-safety,efficiency,e.t.c