We've got a preschooler and a 17 months old, and despite our nursery charging at the lower end of the scale we worked out that if my husband gave up work the savings we would make on childcare and the benefits/tax credits we'd be entitled to on only my salary would mean that we'd be about £50 worse off compared to us working full time.
Surely for the state it's a win that we work full time: instead of having to pay us tax credits and other benefits it gets our tax, plus by using childcare we contribute to the creation of other jobs which again create tax revenue.
By working rather than staying at home, my husband doesn't deskill but keeps his employability and career chances. (In case you wonder - I'm earning more than him, so if one of us would have to give up work because of childcare costs, it'd be him)
It's a bit of a no-brainer, isn't it, I really don't get why there's no subsidy. It's probably less of an issue for those earning very little, so they get help or those who earn a lot, so they can afford it. For those who have on paper a nice income, but half of it goes on childcare, it's a different issue.
For those who worry that helping people who want to work (and financially contribute) to stay in work (and creating jobs as a side effect) may invalidate their choice of not wanting to work - I'd rather have tax money going to helping people staying in the job market, than going to create a situation where it's not worth working.