can you please tell me please where can I find Ukrainian and/or Russian community in Wroclaw?
Expect zero help from Russians or Ukrainians in Poland. A lot of what I wrote about the Vietnamese community is also true for the Russian community. Many are involved in organized crime, so you have to be extremely cautious.
Sorry, but it seems to me that you are counting on the Vietnamese or Russian communities to find you illegal work in Poland. If that's the case, then save yourself the time and trouble and shoot your family and yourself in the head. Your children will be eternally grateful that you spared then the horror of living in the brutal underworld of organized crime.
Wherever you go in Western Europe, there is never going to be any "community" to help you as a Vietnamese person with ties to the Ukraine, except the legitimate native societies of these countries. Assimilation is the only way to success, for you and your children.