I am not sure anymore that a second lockdown will work. The first one worked because it was observed by most; the experience was new. Now people are less observant. Social distancing and masks and so on work well in shops but can hardly be applied in eateries and pubs. You can’t eat or drink wearing a mask 😀. But the mask drops even by people who should be wearing them as in public maintainable workers aggregating in places, admittedly mainly in open spaces but not really social distancing. Where I live, there is little sign of social distancing except in formalised settings.
The problem now is that this government does not like to be unpopular and therefore likes to throw the blame back on to the public, whilst being reluctant to effectively enforce the unpopular measures.
The opportunity has been missed. Lockdown with proper isolation and quarantine measures could have worked first time if proper elimination or near elimination of the virus was contemplated, given that we are an island, and if strict measures then taken to limit reimporting the virus. These last have never been in place and to this day air transport hubs have not been effectively monitored to limit incoming passengers reintroducing more waves of infection. NZ and Australia have had some successes on this line.