Suppose, just for a moment, that some of the Holocaust Deniers are right about the numbers being exaggerated, and only 600,000 (10% of the 6 million reported) Jews were murdered. Does this lower number somehow make ethnic cleansing less atrocious? What if it were only 60,000? Does this somehow turn mass murder into something less evil? And then there are the homosexuals, political dissidents, Gypsies, Slavs, and other groups who were also slaughtered wholesale by a regime bent on genetic pseudoscience. Their deaths are already being hand-waved away by many as well.
Strange that people are so bent upon worshiping political power and the mythology of man that they will dismiss mass destruction by imagining it was somehow less evil if there was slightly less of it. I suppose this is why some prefer to imagine the Holocaust never happened in the first place. It's easier to intellectually justify authoritarianism if you turn a blind eye to its inevitable consequences.
There have been mass killings through history and comparing or arguing about numbers is pointless. I'm British and we have some crimes on our conscience too. I can't verify for myself how many the Nazis killed, but they were such bureaucrats that I expect it can be worked out pretty accurately. Those who manipulate populations into cruelty are very devious and we have to keep an eye on them.
Don't collectivise yourself with the British government. They don't represent you. What they do with the wealth they plunder from your economy is not your fault. There is no "we" in politics unless you are embedded in the political system.