..... woo, there were loads of grammar mistakes in your post.
it should be --> working environment with foreigners
---> of English speaking and writing --> you don't need "it" at the end
--> Please give instructions, thanks you --> that will do.
And I don't really get your title.
Okay, back to the topic:
Suggestion:
1. Practice makes prefect --> just talk to your colleges, it's okay to be wrong. It's the best way to improve. And listen to how they speak!
2. Websites:
BBC for english learner:
http://www.bbc.co.uk/worldservice/learningenglish/Go to "General & Business" :
http://www.bbc.co.uk/worldservice/learningenglish/general/It has dialogs of some specific situations, e.g. in office. Hope it helps
3. About vocabs, you don't have to remember them by reading all over. You should try to use them as much as you can. You will find out it's much faster to remember things in use than others.
4. You can go search on internet about sample dialogs or phrases used often in working.
