It may end up with the UK being less ready for WW1 as the army will lose some of that training and reforms that came with the war. It'll also probably be more jingoistic.
Quite possibly. I think a lot of the problems were apparent pretty early into the war and so I think that they would certainly learn something, as would the Colonial/Dominion forces that were mobilised.
A shorter, easier war would have a lot of impact though - maybe it might delay/hasten WW1 or other events?
It would certainly have a massive impact on the domestic political affairs of the UK and all self governing dominions. Any elections held in the immediate period could be affected in some way.
The Afrikaner populations will be less problematic too. Without the massive concentration camp related death, without the guerrilla war, without the Cape Raid, they may be less united, less filled with hate. Or at least, the Cape Afrikaners anyway, which were a sizable grouping. If the Afrikaner were more fragmented than OTL, this would have impact on any provincial elections, let alone any later Union elections.