I am not in favour of a national lockdown, many areas have relatively low numbers and I don't see the point in crashing the economy in those areas just to provide moral support for other areas, some other areas do need a strict lockdown, so in essence I support the tier system already outlined (plus of course better Track and Trace).
The UK has a few huge flaws which are meaning a lockdown won't work, the most obvious being that it is still banging on about only going for tests if you have symptoms, when up to 80-90% of people, and thus spread, is asymptomatic. They cannot move towards wholescale mass testing as they don't have the capacity, so this capacity saving measure means we haven't a clue whose really got it and how it's spreading- once you do wider testing you find whole clusters of people like universities, but I bet if they had tested some workplaces/factories as well like that, similar would have been discovered.
We have an outbreak at our uni, it's really large, the students had a no moving between household policy, and after two weeks, numbers are down instead of constantly rising.
Lockdowns are all about not shifting between households IMO but the problem with the testing of only symptomatic people will mean we can't get fully on top of this.