The NHS is a creaking hulk that's hugely under-resourced. But for most people, the NHS is the only medical cover they've got ... especially if there's something very seriously wrong with them. And given its under-resourcing, it does an amazing job, relying mostly on people who are not properly financially rewarded. But it will buckle if pushed too far.
At present, we have 4,094 patients in hospital with Covid and the peak in January was 39,254 - about 10x more. At present, about 12.5% are in mechanical ventilation beds, in January it was 10% (i.e. somebody in hospital now is 25% more likely to need a ventilator than somebody who was in hospital in January). Beds, ventilators, nurses, doctors, oxygen, drugs ... these are the kinds of resources that need to be considered.
At present we have about 50,000 cases a day, in January it was about the same. The much lower hospitalisation numbers now show that the vaccine is working. However, as of yesterday we're not locked down and in January we were. Cases per day are predicted to rise to 200,000. If that's correct, it would appear that hospitalisations will be below January's levels. But nobody really knows
a) whether it will stop at 200,000 or grow much larger, meaning that more hospital beds will be needed
b) whether the increased numbers will hit different parts of the population who are more likely to need a hospital bed, meaning that more hospital beds will be needed
These are the two great unknowns that mean that the NHS could be overwhelmed if the guesswork is wrong. As hospitalisation increase, the demand for every resource that goes with that increases: beds, ventilators, nurses, doctors, drugs, etc etc. In the end, something has to give somewhere.
I don't particularly love the NHS, but it's all we have and it is what it is right now. It's there to do a job and I want it to be able to do that job for me or the people I do love if needed. That's the concern.