How do zero hours contracts work?

[adviceseeker22]

Posting here for traffic. So we both work FT, I travel quite a bit for work and wraparound childcare is unreliable. We'd also like to have more work life balance rather than being working and then tired.

Anywho, his current employer is very strict about time off. Sick leave is taken from annual leave, they always have to take the two weeks around Christmas, and there's no real option for unpaid leave, so if for any reason he has to be off (childcare or medical) and he's used all of his annual leave he has to work weekends. I find it all very rigid (especially the sick leave) so I've always thought it would be best if he finds somewhere else. They do pay ok, but it's in a very remote place, and commuting isn't cheap.

One of our neighbours has offered to take him under his wing, (as a subcontractor) however we don't know how reliable that would be.

So, if he got a job with a zero hours contract, would he be able to supplement his hours? (And basically pick and choose whenever he wants to work?)
Tia

Well he can pick and choose but only from what's offered. So if they say we need you from 10pm to midnight he can refuse, but is unlikely to get offered hours again. I speak from a retail pov

Most zero hours have the schedule the week before - however they can refuse the hours - but the following they may not be offered any hours at all.

The company has to full fill the contracted hours first So Janes 35 hours and Ambers 8 hours - etc after that any free hours are given out to zero contract workers

Right, so he might burn the bridges so to speak? All retail here is 8-5, so I doubt he'd do very late or early shifts (but he could be offered weekends).