Mobilization in South Africa was limited because of internal politics;
In WW2 SAAF & SA Army operated in Africa, and the Middle-East, any reason why not further north?
What would it take to enable SA Forces to operate from Britain?
Mobilzation in South Africa was limited because of internal politics; obviously both racial (white/black/Indian/colored) and ethnic/lingual (British and Boer).
Non-white manpower was not called upon, other than in limited and largely auxiliary roles; white manpower, because of the divides among British and Boer, and even within the Boer population in terms of pro-British and nationalist politics, was also limited in terms of who could be mobilized for duty, both within and without the dominion (i.e., the Union of South Africa).
There was a limited mass mobilization of whites for home defense duties; duties outside of the Union required volunteers (the "Africa Pledge/Oath") which is what allowed the services of the South African troops in East Africa, Egypt, and Libya, and then a second level of volunteerism, which is what allowed South Africans to serve as such in Italy.
South Africans could volunteer for the attachment or assignment to the British forces as individuals, and significant numbers did; otherwise, the South Africans fielded two infantry divisions, a separate brigade, corps and army troops, and substantial air forces, for service in Africa in 1939-43, and an armoured division, corps and army troops, and significant air forces for service in the Med and Italy in 1943-45.
Best,