Some of the responses to the OP here are so ignorant and make me so bloody angry, but ultimately make it clear how and why governments get away with so much.
A few things.
They didn't have the capacity to test. They did, if they had done the reasonable thing and accepted help offered by outside labs who were lining up to help knowing how serious the situation was. They didn't and behaved from the beginning as if it was something that would just sort itself out. Fair enough you might say, how could they have known that it would get as bad as it did? Ignoring Italy and Spain, the next thing.
Back in 2016 there was a pandemic drill, codename Excercise Cygnus. From what we know of it, and we don't know all the details because the government has refused to make the findings public, it was scary shit and showed that if we didn't do anything to create more intensive care beds, have more mortuaries in place, more staff, etc, then we would be blindsided by a pandemic and in huge trouble. We know these things from documents that refer to it and from some people who were involved in it. The government have said that they have learned lessons from it but will not say what those lessons are or publish the report.
But, ah, you might say, surely other things were more important and a pandemic was not seen as a huge thread? On to the next thing.
The highest civil emergency risk that the government itself (well governments, this isn't all just Johnson although god knows he doesn't help)? Not terrorism but a global pandemic. That is everyone has known that one would come and it has always been not if but when.
So, our last pandemic drill showed that we were pretty fucked if it happened and we did nothing to improve our chances of dealing with it and we did precisely nothing.
More recent things.
We know that Johnson didn't got to five cobra meetings earlier this year which were to discuss what we needed to do about the novel coronavirus as it was then. This is utterly fucking outrageous. There was nothing done about incoming flights to the UK. Well it was only in China? Yeah, right because we don't live in a global economy where someone from China can go to somewhere else and then someone from there can go somewhere else, and so on. It was stupidity.
Contact tracing was pretty much non-existent. Testing was minuscule. If you had the symptoms, by and large, you weren't tested, you were asked to isolate. This meant no contract tracing of people you'd been in contact with and ... you see the whole thing falling apart.
Johnson talked about herd immunity as did his attack dog Cummings. That literally meant that at least tens of thousands would die, but the expectation was that would be mostly those who were of less use to society, so ... That utter amorality meant that we started too late and we were already fucked and many people who didn't need to die, died and many are still dying.
And then we have all the front line workers who've died because there was no PPE. Nurses, doctors, auxiliary staff, bus drivers, train staff and so on. Mostly low-skilled workers so who cares. And of course the elderly in care homes and care home staff.The staff in care homes are still not getting all the PPE that they need and what in the name of holy fuck is going on when we are still not testing all health workers (including care workers) and testing all homes on a weekly basis because we know they are a test tube for the disease!
Sorry, this is a long rant, but when people say it's not worth getting angry because we can't go back in time and make it all right, that is bullshit. If we don't get angry then we're just making it easier to happen the next time and the next time and the next time. The OP has lost her grandmother and has every bloody right to be angry. Maybe it's not murder but it's certainly manslaughter via the medium of not actually giving a fuck if people died or didn't. And we all should be angry because it did not have to be like this. It absolutely and utterly did not need to be like this. And if you're not at least a little angry then frankly you're not paying attention or you're just part of the problem.