Well the thing is that right now anti-Americanism is on the rise especially in Europe (and even within the US) and with it is coming a lot of historical re-inventionism. A lot of brits and Europeans like to act like they could have handled WW II without needing America, and that our role was "overstated".
Strictly speaking it is true that Britan didn't "do" much except not get conquered, however it was the Brits holding out as long as they did that made it so America could get involved, rally the allies, etc... They didn't win the war, but more or less made it so there was a war. Later propaganda has made them seem more pro-active/offensive than they actually were. Mostly they managed to be a pain in the keister when it came to Germany and a good portion of Europe was trying to dig them out of their own country/cities.
The Russian contribution is another bit brought up to try and make America seem less signifigant. Simply put Russia's big claim to fame was to lose a LOT of people, and hold out getting their butts kicked every inch of the way until logistics / fighting on too many fronts caused the Nazis to lose on that front which DID change the war. The Russian Campaign can be seen more as a German mistake than a Russian success.
As far as the rest of Europe goes, it's a mixed bag. One of the reasons why there was so much propaganda in World War II, and so many lies about portable bone grinding machines, human flesh lampshades, etc.. (I've posted links here before) is that Hitler was incredibly popular throughout the world, including the US. Strictly speaking Germany didn't have that much manpower, it was other nations that chose to side with them (after perhaps a token resistance) that provided the bulk of his manpower.
The unpopular truth is that all of these resistance movements, like the one allegedly in France, are a nice fairy tale concocted after the fact, and to cover the shame of having backed the losing side. Oh sure there were patriots in most countries that didn't like Germany unifying everything, but nothing on a large scale. One of the reasons why France has a bad reputation for example is that they pretty much sold out to the Germans, and then switched sides again when the tide of war changed because basically if they didn't they were going to get invaded by the other allies on their way to Germany.
See, a lot of history is a lie designed to keep the peace. A teacher talking down Europe during World War II is probably going to be correct. It really was a giant mess down there, and the fact that Hitler (who was an international man of the year) was able to take over so many countries largely based on force of personality... well that's what was truely scary about him. Hitler was actually right about 99% of what he said, it's that 1% that was genocidal and whacked that you had to watch out for.
It's sort of like how people will try and tell you that World War II was an antiseptic war with clear cut good and evil, and we always conducted ourselves honorably. That's not true. We were extremely brutal when we fought against groups like the Volkssturm, and groups like the "Hitler Youth" didn't just evaporate because they were inconveinent. However history doesn't show an American GI "heroically" putting a bunch of kids up against a wall and shooting them, or the reality of building to building fighting in the final days when it was troops against what were largely rallied civilians (many probably just defending their homes) while the remaining Nazi leaders were dug out of their bunkers and such.
Understanding things like this is why I'm such a cynical realist.
The bottom line though is that I guess when it comes to the Brits it largely depends on how you define contribution. If they hadn't held out there never would have been a storming of the beaches.
