I'm a nurse and DO believe in the NHS!
I would imagine that vast majority of the population believe in the NHS.
But probably not in it's current form of being a money pit.
As well as sorting out increasing numbers of training positions in the UK for doctors and nurses, and improving efficiencies, charging non eligible patients, etc., there also needs to be a cross-party review of just how far the NHS goes in terms of treatments/support offered.
At one end of the spectrum, we probably all want emergency and urgent life threatening treatments free for all to the highest standard possible. But at the other end, I suspect relatively few will want "lifestyle" issues treated by the NHS such as tattoo removal, facelifts, fertility treatments, etc. Then you have a vast area in the middle where there'll be more mixed opinions such as treating those who have damaged themselves through lack of care such as smokers, alcoholics, drug abusers, etc. (where cost of treatment has to be weighed against cost to society of non treatment), or those engaged in dangerous sports (who arguably should insure themselves for their injuries), or those injured in road accidents (whose insurance should arguably pay for treatment).
If we just raise taxes AGAIN, and just throw more money at it, there'll be the short term improvement but in a few years, it'll be back cap in hand for more. After all, Labour "saved" the NHS twice by raising NIC contributions, and trebling the money spent in the NHS over around a decade, but here we are again!