I think it's happening too fast. A knee jerk reaction by Boris for political reasons. Been the same throughout the pandemic in this country - too slow to lock down and then too quick to open up again.
It's basically putting the responsibility on to the general public/individuals to do the right thing off their own bat - feel unwell, test for covid, if you have it stay home/avoid busy settings for 5 days. Same as you probably would do naturally with flu etc. But will most people do that themselves when rules are relaxed? We've seen what's happened every time lockdowns have been eased - quite a lot of people gone crazy with it straight away. Suspect it'll be the same here, everyone'll just shrug and say they've only got a cold. Especially when home testing ceases to be free. How many people are really going to pay £30 for a LFD kit?
It's easy to just look at the death count, and decide 'well the hospitals aren't overflowing, the bodies aren't piling up, we just need to get on with life'. That may be true, but there's still the economic and logistical impact of a mass spreading virus keeping a significant percentage of the workforce off sick, kids off school, so parents have to stay off work etc.
It's not just like flu. Omicron is way, way more transmissible than flu. It's about the most transmissible virus humans have ever been exposed to. So it'll spread way more and faster, certainly until society has built up a herd immunity to Omicron. Covid vaccines were designed to work on the wild type, they don't give any measurable immunity to catching Omicron (even if they might save you from a bad case of it).
So unless there's an Omicron specific vaccine comes on stream (and we all get yet another booster), we can only rely on immunity developing from natural infections. To put that in perspective, if it carries on spreading at the current rates of around 100,000 cases per day, it will take two years for everyone to catch it. Obviously it won't carry on spreading in a linear fashion, it should diminish over the next 6-9 months. But will probably pick up again next winter (just as most people's natural immunity will have waned). We'll go through cycles of that for a couple of years at least.
So I think it does need an element of managing the transmission rates, but a very light touch rather than rigid restrictions like we've had the last couple of years.