A Question of Balance?

With 3 children aged 6 and under, a house to keep clean and tidy, and week 3 of the summer break starting, things here are moving veeeeeeery slowly, here.

Well, that's not entirely true.  My house is not at all clean and tidy because I have very demanding characters who keep distracting me and seeking my attention. And my children have started behaving like barbarians. But that probably isn't related to the writing.

So how do I balance everything? No, really - how do I? This isn't a how-to guide, it's a desperate plea of a question because I don't have the heart or stomach to cut myself in two.

I keep a notebook to jot things down as they occur to me and I attempt to capture my flashes of inspiration there but, by the time bedtime has been and gone and I have have wrestled three very unwilling children into submission, I am tired.  Tired, and only worthy of slumping onto the sofa in defeat. At that point, most desire to write has left me and it's a slog.

I've tried writing when the inspiration occurs, and my story builds in little fits and starts all day but the danger there is that I become entirely carried away and the children could take my house apart around me, brick by brick (because 6 yr old is a bit obsessed with Lego, and - recently - Jenga), and I wouldn't even notice.  My husband would, though, when he arrived home to a house that no longer existed.  Just a group of barbarian children playing in a large pile of a rubble and a wild woman typing up a firestorm on a laptop fast running out of charge.

Where do I find my balance?  Does a good wife and mother wait until the housework is done, the children are dressed and fed (they are never full.  I've tried.) and sufficiently entertained before she turns her attention to writing?  Or does a good writer ride that wave of inspiration, throwing the ideas on the page while the baby eats dirt in the garden and the two oldest attempt to build an extension upstairs (I have no idea what that banging could be, otherwise)?

Where does the balance lie? Is there any such thing?