This subject has been debated here on AB many times before, and the facts do not change. These people are over here in Britain to work, and the vast majority do exactly that. If there weren't any vacancies to fill, they would go somewhere else.
As long as we, as a nation are content for millions of Brits to stay at home, claiming the dole and other benefits, instead of working, the situation isn't going to change any time soon. The DM can rant and rage as much as it likes but that is the situation.
About 15 years ago, one of my brothers went to work as a brickie in Germany for 2 years, in exactly the same circumstances...there was no employment opportunities here at home, so he went where the work was, as people have done since time immemorial.
The DM is just using the impending arrival of another group of workers, to keep the pot of racism and xenophobia simmering away on the stove.