Talk

The 100k limit is the gross income before deductions for each parent. So one parent might be earning 10k and the other 101k and they wouldn't qualify. However a couple where the parents earn 99k each, 198k combined, would.

The tax free childcare is the same as childcare vouchers.It's nothing to do with the 30 hours.
www.gov.uk/government/news/tax-free-childcare-launches-today-for-children-under-four

The 100k taxable income also applies to tax-free childcare eligibility and it is per parent, not household.

If someone earned £101k gross the family would not be eligible but they should keep in mind that it is taxable income, so there can be ways of reducing that (such as increasing pension contribution deducted at source).

With three children, tax-free childcare could be worth up to £6000 (max contribution of £2000 per eligible child). To get £6000 contribution, childcare cost (which can include employers NI if employing a nanny) would need to be £30k+.