As with so much of Gordimer's works, the idea of culture clash and conflict is a rich reservoir from which to excavate.  If there are specific elements that you have to discuss, I would consult these in the process of developing the paper.  I think that there is much in way of culture clash in examining how the dynamic of the family changes once they flee with July to his village.  The idea of apartheid having created an unnatural structure of power in South Africa is brought out when we see Bam and Maureen actually victim to the same practices in the village.  Their movement is limited, while the emotional stress caused by both political and personal dynamics are heightened.  At the same time, there is an awkwardness in the relationships between whites and blacks in a post- Apartheid South African setting because of the power imbalance that had been embedded in its people.  One of the most startling cultural developments would be how the "master/ slave" dialectic changes once Bam and Maureen begin to live in the village.  This can even be seen on their children, who end up "going native" more and losing the entitlement that being white in South Africa carried.  The ending might be the saddest result of this culture clash, when Maureen runs after the helicopter.  Gordimer's vision of South Africa after Apartheid is one where the lines between savior and murderer is severely blurred.