Can CV19 be defeated by Herd Immunity

It doesn't need to be defeated. We didn't defeat flu or HIV (yet).

COVID19 can stick around if we figure out how to prevent it from hospitalizing people. Or if people do a good job not being spreaders.

There's the question -

possibly

Though in the UK we passed one theoretical modelled herd immunity threshold in April but we still have cases doubling every week currently so that model looks flawed.

Artificial herd immunity, i.e. vaccinating the majority of the population so that you reduce the spread, the hospitalizations and the deaths, is indeed the exit strategy being tried now pretty much everywhere. Whether in the end it becomes endemic but non-threatening, or disappears completely is unknown, but would change very little.

Natural herd immunity (aka: ignoring / letting people get exposed to the pathogen) was tried in early 2020 and we all know the outcome:
[youtube=https://www.youtube.com/watch?v=INmEciVm-6Q]

Immunity from what? This is based on infection of previous virus attack and/or vaccine based on previous incarnation of the virus.
By these if the 'herd' gets any immunity, what surety that the evolving virus with it's new variant will be stopped by the 'immunity'?

Not looking like it.

UK has over 77% adult population double jabbed. Over 85% single jabbed.

However now we have no restrictions we have over 30,000 new cases a day (and still rising) over 6,500 in hospital at any one time and steadily about 100 deaths a day.

Esp with the delta variant (over 90% of UK new infections) it looks to be too infectious for a herd immunity strategy to eliminate it

no, it mutates quiet often. The 4 protein attached to this virus has sign that it was lab made according to Dr Birger Sørensen who is about to register new vaccine in UK.

If the majority are immune because they have had it or are vaccinated against it and it does not mutate then any disease could be considered defeated. COVID seems to mutate though, so might remain an issue, even though it’s lethality is relatively low.

i would think variants will continue to evolve bit i am no expert. believe the experts.

I wish I could tell you.

That’s possibly one of the hopes

We could potentially reach herd immunity through vaccination. That would prevent the spread. It might not completely get rid of covid, but the numbers would be low enough that it won't be an issue.