The UK and South African variants are actually not all that similar. Only the South African variant has large changes to the spike protein. This is why the UK is putting so much effort into stopping the spread of the SA variant right now.
"UK 'Kent' variant with the E484K mutation - it was seen in 11 out of 214,159 samples"[1]
There's been only a handful of cases with that variation in the UK, it is not the dominant strain which the AstraZeneca results you referred to came from.
So despite much heralded increased transmissibility, it has failed to prove dominant despite being incidental in timeline with b117. No great artistry will make it more fearsome than the lack of proof thereof.
https://www.abc.net.au/news/2021-02-03/uk-begins-testing-tho...
Also in a scary development a large portion of trial participants in South Africa were actually reinfected with the new strain because it's so different. https://www.washingtonpost.com/health/2021/02/05/virus-varia...