With no hope of America entering the war against Germany, England would have accepted just about anything that left the Empire intact and gave them a figleaf to cover their pride.
Fine. England can surrender. Sassenachs! We'll carry on.
(It's
Britain, thanks. Although IIRC, the joke that in the event of negotiated peace, Scotland would continue the war was made at the the time.

)
Anyway, this is untrue. Remember, when the Germans invaded Russia, we actually expected the Red Army to last six weeks. We weren't riding our hopes on the Big Us, we were just hanging on in the absense of any political palatable alternatives.
As I've pointed out many terms, Britain effectively sacrificed any hope of great power status or retaining the Empire towards the victory, by pulling the financial rug out from under ourselves, entrusting our war production to America, making promises to India, and expending every ounce of our energy and resources. The only thing we had to showfor this was a defeated Axis (and to clarify, it was
absolutely worth it). If Britain had already, without fully acknowledging it, given everything away to stop the Germans, why would we suddenly be willing to sign a peace giving the German's the domination of Europe we've been trying to prevent any power from attaining for centuries in order to retain things that we were willing to give away?
The plans for continuing the war
after Great Britain were pursued with real seriousness by the government. Eden interviewed the army leadership on how many he could realistically evacuate from Liverpool. We had arrangements, IIRC, for pulling the RAF back to airfields in Ireland, and diplomats were probing the Americans about how they'd relate to a government-in-exile in Canada.
I know people like to live out the fantasies of the arch-appeasers in the interests of their Axis-wanks, but Britain, cliche though it is, actually
is rather averse to surrendering.
And America will not get in the way of the great crusade against Communism; I know Wallace and the other fellow travelers would not like that, but they could not stop it.
You seem to be missing that this scenario does
not create war between Germany and Russia. It creates war between the Entente and Germany and the Entente and Russia (to call the Soviets an "Axis power" in these circumstances would be pushing it). For the Germans to do what you want them to do, that is, make a peace with the Entente and invade the USSR to "crush communism" and starve millions of people to death, the Entente first have to accept German overtures. France won't, I'll wager. Any British government to concede defeat before fighting the war would face opposition from Labour, from Churchill's boys, from the king, from the proverbial taxi-driver...
As no "anti-communist crusade" in alliance with the Nazis exists (if anything, Churchillian rhetoric will create an anti-totalitarian crusade), your argument that America won't oppose it is utter nonsense.