I do not have any fuel numbers for France in 1940, but those stocks would surely be added to the Armada. I have seen several different numbers for the Germans and Italians and these are not complete but I have listed them below, hopefully someone else can confirm or clarify them.
At the outbreak of the war in 1939, the German Navy had its own fuel reserves of around 650,000 tons of diesel oil and 350,000 tons of Mazut.
1940: 256,000 tons
1941: 91,000 tons
1942: 69,000 tons
1940: 521,000 tons
1941: 280,000 tons
1942: 136,000 tons
German (non-Navy), stocks amounted to 2.4 million tons in 1940, in 1942 they dropped to 1.2 million. In 1942, extraction of oil in the Reich amounted to 1.6 million. Imports from Romania and Iran by road through Turkey, and synthetic oil production totaled over 6 million tons of fuel within 12 months. The production of 1943 likewise, even slightly more (over 6.5 million tons).
Italians in 1940 counted 1,479,272 tons of fuel in the naval warehouses, which they estimated was enough for 5.8 months of war.
It is clear that there is not enough fuel to last the whole war, however, there was enough to give the Armada 6+ months of intense operations to fight at Gibraltar and/or Malta. As a "What If" scenario the fuel numbers for 1941 and 1942 would not be applicable anyways since events during that time would have played out differently.
However, if this were reality then who knows if there really was enough fuel to have successfully pulled this off?