First, get childcare vouchers or credits. That gets you tax back on the childcare and saves a lot.
Then use lots of holiday clubs.
Camp types tend to have extended care and so you have time to get them there, drop off and pick up after work. Downside is that they are very expensive even with the childcare tax help.
After school clubs can have holiday clubs too - they are often cheaper.
Childminders often have gaps in holidays, where a term-time mindee might be on holiday so they have room for a holiday-only child.
Sports camps. Watch the timings. I have never used one because they seem to start at 9am and finish at 3, which is no b. good when you start work at 8 and finish at 4...
Science and adventure camps - relatively new, can have extended care. Expensive again so I use for odd weeks in summer to provide variety.
Good luck getting anything at Christmas! Very few clubs open.
And then there's age. Most don't run beyond age 11... so what are you supposed to do with a DC if they are older but can't be left alone because of eg SEN?
Also nanny shares.