The appalling behavior of the Red Army and of the USSR in general at the time is briefly covered in the Wikipedia entry. Churchill in particular seems to have tried very hard to do the right thing.
It's worth noting that the UK was drawn into the war through the alliance it made with Poland in an attempt to contain German acquisitions - the UK was a friend to Poland with no real quarrel. 'Protecting Poland' was their call to war. It's not the greatest stretch of the imagination to consider the UK as doing right by Poland.
The Soviets, on the other hand, had a desire for Polish territory.
This is unfortunately not true. Great Britian declared war on Germany, but provided none support to Poland. This was also the case during the Warsaw Uprising. After the war has ended Poland has been sold by under the Russian occupacion. The polish fighter squadrons that took part in the battle of britain were not even allowed to join the wining parade. They were sent home to what was now considered an enemy state. The Brits may have done a lot of things, but most certailny not the right thing.
Keep in mind that no-one but the Germans were aware that blitzkreig would be as fast as it was. Up until that point, war was a somewhat leisurely affair - this is the exact reason why France fell so ignomiously. War was declared, now we can start shifting things into place while the Poles hold the Germans and... holy shit, the Poles have collapsed in only five weeks.
Same thing happened to the French - the German army moved so fast through the low countries that the French couldn't move fast enough to block them. The last time everyone fought, months would go by with only a few miles of land exchanged. This time round, a few miles of land only took an hour to obtain.
In any case, the UK deserves some credit for hastily allying with the Polish in an attempt to dissuade Germany from invading in the first place. And after the war, the Soviets were ascendent in Europe, with the rest of the Allies afraid that they would continue their march through the rest of the continent. They had a plan to take on the Soviets, but they didn't have the power to realistically defeat them.
"Keep in mind that no-one but the Germans were aware that blitzkreig would be as fast as it was"
Yeah, that's a great excuse. That should be written in the anglo-polish military alliance:
"in the event of any action which clearly threatened Polish independence, and which the Polish Government accordingly considered it vital to resist with their national forces, His Majesty's Government would feel themselves bound at once to lend the Polish Government all support in their power... Unless of course the germans use tanks and move very quickly. In that case, sorry".
The UK did not ally itself with Poland to help them from being taken over. It was a way of saying to Hitler, that he can't just do what he wants in Europe (like anecting Czechoslovakia) without the Germans and French approving it. The war was immenent, and everybody seemd to know that except for Chamberlain. This was only an act of self interest on behalf of the UK, and hey, who could blame them for that?
What you can't reasonably argue though, is that they tried to really help Poland in the beginning of WW2, and that they didn't betray them at the end in Yalta. And the occupation by the Soviets really wasn't much better than by the Nazis.
There was no real plan to take the Soviets on, because the Allies had no real stake in it.
What you can't reasonably argue though, is that they tried to really help Poland in the beginning of WW2
The UK allied with Poland in an attempt to contain Germany, as I've already said. It's normal for countries to make such big gestures in their own interest. Should the UK have just allied with Poland out of a sense of charity? What in particular had Poland done for the UK before this time, to demand the UK's unquestioning selfless military intervention? What became Poland was, after all, part of the central powers that opposed the UK in WWI.
And, like I said, no-one knew how rapidly Poland would fall under Blitzkreig; the mobility of the German armies was still not countered by the time they invaded France months later.
The war was immenent, and everybody seemd to know that except for Chamberlain.
Chamberlain was buying time to rearm the UK. I've always found it amusing that people take the position that the UK is responsible for 'letting Germany annex Czechoslovakia'. Apparently the other powers in the region didn't have a moral responsibility to protect an unrelated central European country, only the UK.
One wonders, if it's all about morals rather than capabilities, why Poland didn't step in and prevent Germany from annexing Czechoslovakia?
There was no real plan to take the Soviets on, because the Allies had no real stake in it.
The rest of the Allies had a huge stake in preventing the Soviets from dominating Europe. They just had no way to feasibly follow it through.
I'm not sure the UK was in much position to directly help Poland at the start of WW2, especially when Poland ended up being split between Nazi Germany and the Soviets.
At the end of the war Churchill did ask the military to come up with a plan to free Poland from Soviet control by force - but that was never going to be a realistic option, even with US assistance:
It wasn't the case with The Uprising. There were serious efforts to help from the air. The Soviets made this hard though. And yes, treatment of Poles (and Cossacks and others) was very bad). http://en.wikipedia.org/wiki/Warsaw_airlift
It certainly is. Over the last few years there seems to have been a fair bit of WW2 history written that is less loaded with Cold War prejudice. While lots is still unavailable it has made for some interesting reading. I hope this carries on as it's been fascinating.