The moment Chamberlain leaves office and Churchill becomes PM, there is literally 0 chance of Britain conceding anything to Germany. If you read the War Cabinet papers, this will become clear. You have to remember that in 1940, Britain was still considered by many in Churchill's cabinet as the premier world power.
I have also not seen anything that would indicate Hitler would abandon his lebensraum in France - expanding the German straight was, after all, a major objective of his.
"Wilingness to fight", aside from bravada and chest pumping, tend to be extremely circumstantial."If this long island story of ours is to end at last, let it end only when each one of us lies choking in his own blood upon the ground"
I think the War Cabinet Crisis perfectly outlines Britain's willingness to fight to the last drop of blood. People like Halifax and DLlG were open to the possibility of a negotiated surrender, true, but few others were.
Had Italy pushed succesfully in the Med, Germany made treaty with USSR and attacked/perswaded Turkey, faced with invasion into Iraq and maybe, pressure on Persia, UK could see things different. Had a succesfull submarine blockade be established, things could get different as well. Obviously, it is easy to do the chest pumping if you`re sure that your position is safe, which it pretty much was in 1940.