It's a problem that middle class parents feel they can't afford to have additional children, when their taxes are supporting low income families to have more children than them. That is neither fair nor sustainable.
The high cost of childcare and the huge price disparity of housing in different areas of the country throws income redistribution way out of whack. You end up with a single mother having the same disposable income regardless of whether she earns £14k or £70k. Again, that's neither fair nor sustainable.
I think the best way to tackle the inequality which childcare costs bring (women being forced out of work, or working for nothing - just to keep their career going) would be to extend state educational/nursery provision to the preschool years for long enough hours for parents to work, like France and Germany have. Ideally with cover during school holidays too.
I know the government have tried various things like free nursery hours, but they are so under-funded and so limited compared to normal working hours that nurseries just make up the money by increasing the cost on the non-funded hours which parents have to pay in order to work. It doesn't actually help parents to work: in fact working parents end up funding non-working parents even more!
It needs to be state-managed, with employed pre-school teachers and government-owned premises, like in France.
It would be very expensive (maybe £30 billion? Ie 1/3 of the current education budget allowing for fewer years but higher ratios). But so is the welfare budget at £100billion for working age benefits excluding incapacity and disability benefits. That should go down a bit when the childcare disincentive to work goes. There are great incentives at the benefits income level so that 'working always pays' but that disappears at the tax-contributing income level, where it's arguably more important.
Families not having to pay for private childcare would also leave more head-room for increased general taxation (every 1p increase on basic tax raises £5.5billion). Each citizen benefits from their own childhood education and then pays taxes to cover it for the next generation, so over time it's fair for this to come from general taxation even from people with no children themselves.
It makes it fairer between the genders too since even absent fathers would be paying the higher tax rate to support childcare costs, instead of it falling so heavily on women. 25% of families are single-parent in the UK, overwhelmingly financed mainly by the mother. It's time we recognised that reality.
And by removing the huge financial disincentive to having children, we might actually increase our birthrate - which has huge long-term benefits for the country.