In a perfect situation (and I appreciate this is just fantasy) I'd
1)get a load of testing materials in (to test for having the virus and to test for antibodies)
2)make sure we had a huge quantity of biohazard suits ready to go
3)give every citizen a generous payment to buy food/supplies for the next month
4)with warning, have a very full lockdown. Absolutely no leaving the home (unless ill) for 3-4 weeks unless you are a vital worker.
5)if you're a vital worker (so a medical worker, a utility worker, etc) then you get issued with biohazard suits/on site showers and so on and do have to carry on working.
6)hopefully if everyone sticks to it really rigidly (knowing that it will be for a shorter time), then hopefully by the end of the 3-4 weeks, the only people who will have moved around at all will be the vital workers and those who have developed symptoms or otherwise ill, and those who've recovered and been sent home.
So everyone who needs it should then be in a hospital/care setting, and can be thoroughly tested. Many make still take time to recover, but with a smaller, core team caring for them (and perhaps based in nearby accommodation) who are given huge amounts of PPE, hazmat suits etc.
Anyone who somehow slipped through the net should be immediately tested, any contacts notified and quarantined. But hopefully the virus in the community will have died out after those 3-4 weeks because it had nowhere to go.
Then all we need to control after that is the borders, temporarily. I mean, if we're going for a utopian situation then every country in the world could simultaneously lock down and do the same for this few weeks.
It'd be a grim few weeks, but it would hopefully then be over, followed up with very strict testing for symptoms and antibodies until vaccines are discovered.
I'd reward the NHS staff and key workers with pay rises, and we'd encourage more working from home wherever possible to keep down pollution, invest a huge amount in green technology so that as a country we could provide our own electricity and power from the elements (especially the sea/wind/solar), build small farms in town centres where shops have closed down, to provide more food and give more green spaces, look again at working hours to make them fit better around family life and school timetables, so that we can make full use of parents' potential to work if they can/want to, and still have lots of quality time with their families.
Eventually, as a vaccine gets developed and Covid vanishes, hopefully we can end up with something good coming out of this terrible tragedy, rather than going back to a setup where people are struggling from day to day in insecure work and living conditions. Wellbeing could rise, health outcomes improve, and then if another virus comes along we'll be far better prepared to stop it early.