Simply false. Yes some can but this is a very small minority.
Most white English speakers can find enough ancestors to get UK residency (and many already have). Afrikaners are SOL.
A few years ago the number was 800k who either already had or could immediately get a UK passport (not just residency), plus 200k with similar status in Portugal. So for immediate residency in Europe that’s about one quarter of the white population and at least half of the native speakers.
In other words, you don’t know what you’re talking about.