My opinion:
Vaccine roll out is on schedule. Just did a rudimentary calculation based on number of people in the priority groups/current vaccine roll out and I get 16th Feb for when they’re all vaccinated.
Give it two weeks after for the last of those groups to build up some antibodies
Takes us to March - first vaccination may have a low % efficacy at preventing disease... it has a very high efficacy for preventing hospitalisation
NHS - no longer at risk of being overwhelmed by then. Cases are already falling - hospitalisations/deaths have a lag so they will start to improve in 2 - 3 weeks to follow the drop in cases.
I predict that by mid March, they will start moving counties down through the tiers. With many starting on lower tiers due to low infection rates.
After top priority groups are vaccinated, they will focus on simultaneously giving second dose as well as vaccinating all the other adults. First dose numbers in this period (from mid Feb) will be much lower than now, but 2nd dose will be high.
We will come down through tiers (pretty rapidly I think - so you’ll have mask wearing/SD but most places will be open) until probably about end May/beginning June when lockdown/tier system will end. They may still keep masks/SD for the rest of the year.
They will track the original subjects of the vaccine trials so they know when protection starts to wear off, giving them a good 6 months notice to ramp up supply and to get ready to roll out again.