I personally do not think a plan such as that would be sensible.There is a scientific view that leaving some sections of the population unvaccinated gives the virus a transmission path albeit a reduced one. This allows infected people to develop resistance against the actual virus not a vaccine. It has been said this could be a benefit as cutting off all paths could lead to multiple mutations. But I guess the juries still out on such theories.
It is generally accepted that as long as the Covid-19 virus is as transmissible and does cause such major symptoms, and we have no simple way to to treat them, breaking the transmission routes is the only practical way to go.
Lock downs are one tool, and the first one we had in March 2020 showed how they can keep a lid on the spread of C19. But the one we are in at the moment has been significantly less stringently adhered to and the result was clearly demonstrated by the spread of the Kent mutation which seemed to spread as if there were no lockdown I know it didn't help the lockdown was slow at being introduced, but even after its was, the virus continued to spread at an alarming and almost unhindered rate. I am sure there will be many studies carried out to discover why the 2nd lockdown was so much less effective - I'm sure there are lessons to be learned from it.
So if you can't physically stop the export of the virus from and infected people, you have to try and reduce the populations ability to become infected by the virus. This is where the vaccine process becomes so important.
Unfortunately there is no single transmission route for an established virus like C19 there are multiple paths. If the vaccine is only used for a few of those paths, it will simply bypass them through the unprotected paths. Its very much like what would happen to traffic flows when one route is blocked, we find a way round them. So if you want to stop the traffic completely, you have block ALL routes. In other words cause everybody to develop immunity.
Practically it makes sense to try and identify the most frequent transmission routes and those with the worst consequences, and prioritise them and flood them with effective vaccines, then apply vaccines progressively form worst case situations down to the least worst. It does seem the Gov't has tried to do this, but as with most of the journey of the is pandemic we have no prior plan to follow it has to be created largely as we go along, based on on going results and advice from professionals.