Depending where you are, some day nurseries will run a holiday club for under 8s. There are 2 round us that do this. Places are like hens teeth. Siblings of children already in the day nursery are offered spaces first. Then children who attended the day nursery and still on the nursery mailing list get next dibs. Then any unfilled spaces (very rare they are unfilled and if there are any it's usually 1 space or a space on odd days) are advertised on local FB pages. They are snapped up very quickly. My friend made sure to get her little boys name down for this nursery within months of birth as she needed the full time child care and knew someone who told her they also do holiday clubs.
Other solutions include
Finding a term time only job. Or speaking very nicely to your employer about going term time only.
Buying extra leave or building up TOIL and balancing leave with a partner to cover the weeks.
Working for yourself or family business and been able to choose hours and weeks worked (just because you work for yourself doesn't mean you can have weeks off work though).
Grandparents, family members and friends swaps. Friend swaps are easier in the older years.
Been super organised (which may include setting alarms and reminders for the 1st September/ 2nd January) and booking one of the only 3 holiday clubs (within an hour drive) which runs 8am -5pm. Otherwise again been super organised with multiple spreadsheets to cobble together care for the holidays around the 10am -2pm, 9am-12pm, 9.30am - 3pm holiday clubs that run.
Getting your child into clubs/ activities which run holiday clubs as round us priority places are given to those who attend said club. So dance club goes out to those at the dance school first, then advertised to the masses. Same with football, rugby, gymnastics, acting.
Cobbling together multiple bookings at multiple clubs as everywhere only offers 2 or 3 days a week or 1 week of the holiday. So week 1 of summer is gymnastics club, week 2 Tuesday and Thursday is art club but only 9-12 so someone (usually grandma) needs to collect. Then no other clubs are running that week, but Wednesday they have a rocking horse poo space at day nursery 8-5. Repeat for all holidays.
Or sacking work off altogether.
I forgot, praying to all God's of all denominations that whatever childcare you have cobbled together does not fall through at the last minute. In truly desperate times you also make offerings and empty promises of conversation if the childcare does not fall through.