I would be scared as to the precedent set. It is one thing to lockdown as an emergency response (though I always felt that the harm outweighed the benefit) but if we lockdown or impose severe restrictions again, then lockdown becomes normalised as a way to deal with insufficient NHS capacity. The idea that my and my families life will be controlled on a long-term basis by whether hospitals are busy is frightening.
If we "need" to lockdown when 95% of the population have antibodies and in relative terms a tiny percentage of the population is actually severely affected by covid, the same justification could apply every winter and to infectious diseases other than covid. Healthcare capacity is always a constrained resource in every country in the world. A new lockdown would show that our main value as a society is now maintaining "health" which has been very narrowly defined as ICU bed capacity - at any cost. So millions of people lose their livelihoods, social life, financial security and general wellbeing (and often also mental health and long-term physical health) and all the other things which make life worth living to marginally increase the chance of someone else having an ICU bed (assuming that the justification for lockdown would be about NHS capacity and not just about case numbers).
And when imposing moderate restrictions doesn't work - which we essentially know it won't from experience, particularly with the delta variant - then we impose severe restrictions and when they don't work quickly (which again they won't, as we already know) we impose them for longer. And then to "avoid another lockdown" we probably keep masks and social distancing and a load of other things which degrade everyone's quality of life (particularly children's) afterwards. And they become normalised over time too.
And by that time my son will have spent the vast majority of his life living under some form of restrictions and in a toxic culture which conditions people see each other as dangerous biohazards and puts up literal barriers between them. And long-term he and his generation will have to pay for this.
I would also be concerned about the economic impact, which seems now to be ignored by the press and government. The economy thrives on certainty and part of the damage caused by being in and out of lockdown has been the erosion of any certainty. Why would you start up a new business if it could be closed down indefinitely at any moment or forced to trade in conditions which can't be profitable. You can't link the functionality of your economy to availability of hospital beds and expect it to prosper. The unlocking was probably described as irreversible in order to create some certainty. I think we are taking a huge risk with the economy (and therefore our ability to fund public services like healthcare in future) by printing money like we have been. Maybe it will work out ok but it could easily be catastropic, even more so than running out of healthcare capacity in the short-term.
I've no idea about compliance. I wouldn't personally comply with any rule about not seeing my family. But I think people are naturally quite compliant (and many quite like being able to turn away from society and stay in a bubble) and the government's behavioural scientists have so far managed to create essentially the behaviour they intended to. I don't think they will be able to create the same level of personal fear again though. And I think if the financial support went or was reduced you would see a very different response to lockdown than what we have seen so far.