Earlier quoted context omitted.
The NHS also offers a range of other talking therapies /counselling, e.g. counselling for depression. The waiting times here can be shorter than for CBT. If you're in dire need for help (depends on your scores and initial phone interview), you will be seen or referred quickly (within less than a month). Any GP will refer you. If you need help with your mental health, just ask your GP for a referral, fill out the form…
I think most people who suffer from actual depression, not a just a bout of sadness need long term treatment. The NHS is poorly provisioned in this way, sadly. Just like a diabetic who needs insulin everyday people with serious psychological conditions need regular treatment. I'm lucky enough to be able to afford it, I don't know how I would cope if I couldn't.
As far as I know, acute occurrences tend to be more intense (as experienced and reported in standardised tests) on average than chronic ones. Here, the risk of, e.g. suicide is also highest. However, long-term depression has a much more long-lasting impact on one's life, so I don't want to downplay it in any way.
Acute episodes tend to have a duration of only a few weeks or months so short-term therapy can be of great help here.
I agree that chronic depression requires long-term support. Your analogy with insulin and diabetes is excellent. And yes, the NHS falls short in this area, unfortunately. It would be great if more people could get the care they need and I hope it will become possible.
So yes, the NHS is not without its flaws. But considering the little funding it receives, it provides excellent care. It just shouldn't be so underfunded. I also think that it is also remarkably well-organised compared to other countries, e.g. Germany, where everything is much more bureaucratic and expensive. I also think it's significantly that countries with more privatised health care like the US.