Can we claim that the UK's response was faultless when we can see that other countries have had apparently better success in combating the virus's spread?
Nor is this question conditional on the UK being the only country, or one of a few, to have "screwed up" by this measure. There are clear questions to be asked for example about the response in, in no particular order, the USA, Brazil, China, Iran, and plenty of others. Just because almost everybody is making a mistake doesn't mean that the mistake was unavoidable.