I'm no lover of Johnson but I am not sure what people actually object to. I find the Chief Scientific Adviser and the Chief Medical Officer very impressive and Johnson, for once, does seem to be closely following the scientific advice. I found their arguments for when and why they are taking, and in some cases not taking, particular actions pretty convincing.
Italy may well have reached the stage where more drastic action is needed.
There seems to be a lot of people who think that there are actions that a government can take that will stop this virus. I don't believe there are. It is a new virus. There is no immunity in the population at all. There is no vaccine. Under those conditions the virus will progress through the population and the majority of the population will catch it. The UK is working on a best worst case scenario of 80 % infection over all. Sadly a significant number of people will die, as they do with seasonal flue every year. The UK government response is to try to delay the peak and to flatten the peak over a longer time period. This does not reduce the overall infection rate but it greatly reduces the instantaneous pressure on the NHS and so allows them to provide the maximum treatment to those most badly affected. That is probably the best way to minimise the death rate. A steep narrow peak would totally overwhelm available medical care leading to aggressive triaging and those least likely to benefit from treatment being left to die. Only time will tell.