I just can’t see it happening. Whenever it’s suggested, the discussions are fascinating. Some people want an extra week at February as they fancy skiing (most people don’t), some people fancy an extra week in June but accept that this would be a nightmare for GCSEs. Some want an extra week at October-some don’t. Some schools seem to do this in October anyway by jiggling insets around. Most accept that having 3/4 weeks off in the summer would be a logistical nightmare for working parents to try to get the weeks they want off when the rest of their workplace wants the same ones.
The only people who do seem to want long days and short holidays are either people who hate teachers (those who write in the comments section of the DM!) or those who want to pay less money on childcare. But the majority of parents don’t really want their kids in school longer and more just so that other people’s childcare problem is solved.
There is no single alternative that the majority would be happy with, which is why I can’t see it ever changing nationally.
Better childcare facilities should perhaps be a focus, but this has nothing to do with school and shouldn’t be the responsibility of heads or teachers.