A surprising number of non-Afrikaans-speaking South Africans, whom more nationalist Afrikaners called 'the English,' lived in SA just prior to era of the 'total strategy' of Botha. Anyone who would choose to go there would not be subject to enormous harassment, depending on where one might live. In the cities, especially Cape Town or Johannesburg, such populations did exist, and some were visibly hostile to apartheid even though they did not openly defy it until much later. In smaller towns or the countryside of the Highveld Boer strongholds, the matter might be a lot different. You'd be equal to an Afrikaner in terms of rights (if you were an SA citizen), but the ways that people might treat you would vary. Overall, however, the fact that you'd made the choice to relocate to SA at a time when SA is a pariah state might raise more eyebrows among your UK relations than in SA itself, unless you (say) expressed open dismay at the conditions apartheid created, or broke the unwritten rules of racial hierarchy that governed domestic work, transit, etc. (Sindiwe Magona's To My Children's Children has a powerful recollection of her service as a domestic laborer to a member of the British consulate, which is interesting because of all the ways that it differed, but of course that person was part of the legation. It's a good book to read, anyhow.)

From the 1920s until the 1960s, there was a notable push for rapprochement between white Afrikaners and white English-speaking South Africans as people with a shared heritage was significant among educated people, even as populists tried to focus on Afrikanerdom as the only 'egt' South Africanness. (F. A. van Jaarsveld's The Afrikaner's Interpretation of South African History, 1958, is a good example of this kind of writing.) That said, nationalists (who weren't the entirety of Afrikanerdom) did like to point to the camps of the SA War as a crucible for identity, even though a distinct minority ever experienced them, and most Afrikaners remained loyal to the Crown (or at least sat out) during the 1899-1902 conflict.

But it's also true that the National Party and Afrikanerdom were having some problems by the time you mention. By the 1970s, one problem for the Nats was that they were moving away from total support of Afrikanerdom as their base, and towards placating international commercial, capital interests that could keep the country's economy afloat. This would hurt them later on and, along with the extension of conflict across the region and heavy-handed actions against what many white voters saw as reasonable demands by Black workers, alienate a significant mass of voters. The paradox of needing more skilled and semi-skilled workers than were available among whites, and yet demanding an educational system that did not train people for the same and a white labour movement that didn't want such doors open, was a crucial piece in the confusion of edicts that made the Durban strikes of 1973 so powerful and, of course, led to the 1976 Soweto Rising over the staged introduction of Afrikaans as a medium of instruction equal to English. So for a variety of more nationalist Afrikaners, even the NP under BJ Vorster's ministry wasn't devoted enough, and they split from it. Not even PW Botha could bring them back, but then, he was the one who started trying to negotiate exit strategies with apartheid's foes that would retain white primacy. Such was unthinkable for the Verwoerd set of the 1960s, who extolled the virtues of hewing to a purist vision of grand apartheid that had already by then proven to be impossible and utterly inhuman.

To get a stronger idea of how these relationships worked and fractures within the party, I'd look at Hermann Giliomee's The Afrikaners 2nd ed (2009). It's available in Afrikaans, if you decide you'd like to practice.

Ah ok so on the grand scale of things I’d be ok, some may grumble but they’d be a minority.