You can only blame the Government so much here whilst still remaining logically consistent.
I'm not quoting all your post as it's too long and I've wrote enough, but do you not remember "herd immunity"?
Our medical experts were clearly not experts when pushing this "herd immunity"? Is Cummings an expert? Every other expert from WHO and other nations that were ahead of us were saying "Test, Test, Test". An expert does not ignore advice from those that know more than they do, and were ahead of us. If we picked and listened to those experts then thats also the fault of the guy that's picking them.
This "no test is better than a bad test" line is absolute balls. Most get a temperature, so just by checking everyone's temperature before going onto public transport, into an office, into a busy area would have worked wonders (like it did in asia). We could have tracked peoples movements with a QR code that did not need to hold anyone's personal information. Or if we wanted to go a step further could have tracked peoples phones temporarily. Yes there's possible data protection issues, but these are far trumped by the positives.
I'm not blaming Boris specifically, but he's the figurehead of his government, which is to blame and Tories have been in power long enough to make any changes that they wanted to.
We had two more weeks notice than Italy, and based on the doubles every three days idea that two weeks notice could have took our infection number down by 1/16th. Based on 1 = 2 = 4 = 8 =16 (after 12 days). Even if you took that to 9 days, roughly like what we are behind Spain, then it's 1/8th.
People mention Japan and Korea as they have a lot of interaction with China, so it's not unfair to assume that they had more people with Covid initially visit them and their measures just put a slow/ stop to it. Also Asian countries are the experts in these situations, so we should have listened to them.
A big problem that we have is that this country is just so ignorant (I say country as it's mainly an England problem), but this has been fuelled by the last 10 years of Tory rule, along with brexit and this "we don't listen to experts, nobody can tell us what to do, nobody knows what will happen" malarkey.