I realise it's awkward sorting out childcare over long school holidays, I've had to do it myself at times!
I have to agree with PROUDNSCARY though. Of course it may work fine for you all and I hope it does. The last few summers though, our neighbours have done this who live next door but one, normally for two weeks at a time while my friend is at work and her dh works from home.
They're nice kids and play a lot with our dc's anyway,but as the summer wore on I found the role of "childminder' being foisted on me by default
Their kids would always be in our house or on the patch of grass in our corner of the street. Even on the days I said no to them coming in they were constantly knocking on our door while playing out! One of them would have fallen over and needed a plaster, they'd be hungry/thirsty/need the toilet and tell me their dad was getting annoyed with them going in and out while he was working so it was "easier" to ask me
There were also times when we were going out but their kids wouldn't leave our front garden as it was more "fun" than theirs, so I would have to go over and tell their dad there would be nobody "supervising" at our end of street, so best that he went and got them! He didn't look happy at me interrupting his work but what was I supposed to do?!
There was one day where my friend actually asked me to have them all day as BOTH her and dh were needed at work. Now this was a day we were going to be in anyway and feeling exhausted with all the demands from their kids over the summer, I just didn't want to do it AGAIN! Felt obliged to say yes though, as it would have been too awkward if I'd said No, one of them would have taken the day off only for them to see we were at home, and for their kids to be playing out with ours anyway!
If it works for you as a family then I'd do it, but you'd need to be careful that other parents in the street wouldn't be under pressure because of your circumstances, and try to have firm guidelines for your children when you're not there. I know my friend's dh was working, as yours will be, but I didn't see him out there AT ALL offering any supervision for his kids, even when his youngest was screaming blue murder as a happened frequently, (he's 5, coming up 6). Other neighbours were coming running out so he MUST have heard him!!