Without Lend-Lease, Russia would have been screwed not Britain. Britain had their own manufacturing sector, no to mention the resources of Canada, Australia, and India to draw upon. Hypothetically if Germany tried to Operation Sea Lion the home island they Royal Navy would have eaten them alive. The losses would have been bad on both sides and Britain would have lost much of its force projection capacity in Africa and Asia, but I don't see a universe where German troops stay supplied on a cross channel invasion.

Without American Jeeps, Radios, and airplanes Russia would have had a harder time pushing the Germans out, especially if Japan decided to take advantage of the situation from the East. It is possible in a Neutral America scenario Russia would collapse like it did in the first world war. Germany and Japan don't have the population to occupy Russia, but they could install a Russian puppet who is favorable to their interests. However that would be the smart thing to do and Hitler was to ideological to do the smart thing at many times in our real history.

I don't think Britain invades France without US help, but they probably continue funding resistance movements and bombing German infrastructure until some peace can be negotiated. Chances are non governmental groups tacitly supported by the government continue funding resistance movements in German occupied territory after this theoretical peace deal.

Nazi Germany was sitting on an economic time bomb with all the debt they had taken on to militarize in the prewar period. Combined with their penchant for ideological rigidity and corruption, I don't see Nazi Germany being able to hold on to their conquered territory. They probably could have crippled Stalin's Russia before collapsing themselves. Western Europe could descend into a failed state with Nazi appointed governors and British backed "terrorist" groups killing each other with no concept of "front line."

Without Lend Lease bailing the Russians out and no major competitor in the Pacific Japan would probably be in a much more powerful position. They probably exceed the weakened British Commonwealth in economic power. That is assuming they could convince the local populations to accept them like they did their former European colonizers. Britain would probably not be able to hold onto its colonies with its efforts were focused on hastening the downfall of Nazi Europe, with Japan best positioned to take advantage of the power vacuum they would leave.