tens of thousands of Poles who chose to join Nazi forces. ... they would have ended dead or in a concentration camp.
Yet more fiction about history from you, how surprising. The Nazis didn't waste resources killing people who refused to sign the DVL, or even sending them to concentration camps. The thing people were trying to avoid by signing the DVL was being conscripted as labourers. The Mrs' grandfather was given the choice of signing the DVL or being sent to work in Germany. He took the later option, some of his friends signed up and were then conscripted into the Germany army, they never came home.
I love the way that you try to categorise all those who volunteered for the DVL as being something other than Polish.
Your claim about deserting as soon as they could is hilarious; how do you support that claim in light of the fact that only 5% of the Poles who deserted the Nazi forces and joined the Polish army did so before D-Day.
As for what Britain could have done to Poland, (I have just seen the question),well, as I said before it was the Phoney War. Period.
So you choose to simply repeat a lie rather than going into detail about what Britain could have done to help Poland in September 1939 but failed to do. How surprising.
There are, however, other bitter things worth mentioning, like the Victory Parade.
You mean the parade to which Poles received a more privileged invitation than any other nation? Both of the self-appointed Polish governments were invited to send representatives: the internationally recognised government was invited to send an honour guard to accompany the parading of the Polish flag in the same way as other non-commonwealth nations who had take part in the war on the allied side; and the London Poles were invited to send pilots to march in the parade alongside other airforces which had flown from bases in Britain. The Polish government accepted the invitation and then didn't bother to send anybody, while the London Poles rejected their invitation because they didn't think that they were privileged enough. But more than a few Poles have been lying about those events ever since.