Poland was savaged during WWII for no good reason and completely unfairly.
From Poland's view point it was savaged for no good reason but from the German and Soviet view there were plenty of good reasons—Living space in the East for Germany and revenge for Stalin! This was unfortunatley Poland's destiny regardless of any friendship treaties it had signed with Germany and USSR earlier and with Britain and France afterwards.
However a big mistake was that Britain persuaded the Polish government to delay mobilisation (which it did) in a vain attempt to give diplomacy one last chance.
The sensible thing to have done would have been to prevent the imposition of communism.
As Stalin had millions of communist Red Army soldiers sweeping across the soil of Poland by 1944 what sensible plan was possible to stop them and why would they want to do that? Unless you are suggesting that the western allies should have turned against Soviets at this point in 1944? What would have happened if they had: the USSR would then most likely have sat round the peace table with the Germans again so what would be the sense in creating that scenario. By 1944 Poland was a communist contolled country by virtue of Red Army already on its soil.
At the end of the war in Europe the western alies believed it still needed Stalin's mighty Red Army to help defeat the Japanese especially in Manchuria... as it turned out the atom bomb obviated the need for Stalin's support... but by then the die was cast.
Churchill was just happy to bask in his glory.
And rightly so—for all his faults he rallied a nation to the eventual victory over the German's. If pompass ass he was he also got the job done for Britain at that time; he defended Britain's interest above all else; as any nation's leader should!