I've recently asked this question regarding a maximum earnings and reward cap. So they work it out on average and if they think that they are paying for more childcare than your working hours need they will simply ask you to provide a breakdown of your working hours to evaluate the reward. However that will also depend on if its a single or joint claim and also if you are "looking" for more work under the usual breakdown of working commitments depending on child's age.
85% up to 1k I think it is for 1 child. You can’t claim 30 hours back but only work 15. There is no minimum x
You just have to be earning NMW but the number of hours of childcare can't be excessive If you're working 16 hours they wouldn't pay 40 hours of childcare for example
I believe you have to earn more than your childcare fees for them to help but I could be wrong x