Why do Polish people talk so disrespectfully of Britain and Francem regarding Germany invading Poland?

Britain declared war on Germany and so did france for invading Poland,this is not light thing to do,sure Britain appesed the Germans until it was too late,but they commited themselves to full on war due to Germany annexing Poland. Britain lost an empire fighting the German war machine in ww2, and millions of men,just visit any village ,town or city up and down the U.K to see what a sacrifice the U.K laid down in WW2. And why do Polish people think that the U.K owes them a living or that they are doing us a favour with the Polish migrants that have overwhelmed this country in search of money,Polish and Eastern European migration has done nothing but push down wages and left a whole genaration of British youth unemployed(1 million 16-25 year olds unemployed),whilst at the same time making a foreign people rich on our backs.