How many men in Africa bordering Italy can Britain/France free up?
In Egypt the Brits had the 'Western Defense Force, which amounted to a understrength corps. There were some other regiments. brigades, & division HQ scattered about Egypt & on the Sudan/Ethiopian/Somali borders
On the Franco Italian border there were some fortification regiments blocking the mountain passes. Assorted reservist divisions & corps HQ/support groups did their post mobilization work up in the region, so technically they were in reserve, until they were moved north. When Italy attacked across the border the fortress regiments & some Alpine battalions stopped the Italian attack with little assistance from the regional reserve.
In Africa, on the Tunisian/Lybian border initially there was a corps HQ & three divisions of reservists. I don't know what mix of 'Active, second wave or A Series, & third wave B Series they were. They were installed in a fortified or entrenched zone, and were described as having limited mobility. Some additional formations of fourth series mobilization were formed in Tunisia and technically were in reserve for the border defense. But, those were hardly formed, little trained and, unequipped in May 1940. They weren't really expected to be ready for combat until the end of the year or later.
My take is the Allied forces deployed to face Italian armies in May 1940 were a mix of units capable for the situation there, but of limited value in the battles on the Franco/Belgian plain. In terms of raw manpower a couple hundred thousand. In terms of equipment and training not a lot.
The Italians did have a couple of armored divisions, and a 'Fast Corps' of motorized infantry divisions. These were obviously not in the same class as the French DLM or the German Panzer divisions. Still Hitler ordered halts four times for the mechanized thrust to the Channel. the first three times harder got the orders canceled quickly. A corps of a couple motorized divisions and some tanks counter attacking could have caused one of the earlier halt orders to stick, giving the French and Brits a couple of badly needed days. More likely tho the senior French commanders would have dithered and canceled any Italian attack until too late.