i am not well versed about the north african campaigns, but if the british wiped out the italians in north africa then would the germans have not sent there infamous afrika korps over?
If the British concentrated solely on North Africa to the point where they kick the Italians out of Libya, and possibly then got the French colonies in North Africa to switch sides and rejoin the fight, the Germans would have zero ability to deploy troops to North Africa.
Operation Compass, which the British launched in December 1940 was a massive success against the Italian army in Libya, taking over 100 thousand Italians prisoner, along with hundreds of tanks, cannons, and large amounts of equipment. It was the first major victory any of the allies ever had during the entire war.
Unfortunately, Churchill ended up pulling several divisions to go to Greece, along with large amounts of naval and air assets, which in the end did nothing to stop Greece from falling.
Come spring of 1941, the Germans showed up, and managed to push the weakened British forces back into Egypt.