"What planet are you on that you don't think affordable childcare is more of an issue by a factor of about a zillion to people in the UK across the wage brackets, than tax deductible cleaners?"
Who do you think said that?
I certainly didn't.
Making childcare tax deductible would be enormously costly, as outlined by Quattrocento earlier.
How do you want to pay for it? Or what do you want to cut to pay for it?
I'm all about tax-deductible childcare, but I don't see why I should be against this measure unless it includes childcare.
The argument that "something else would be better" has nothing to say about how good this is.
It's contradictory to say that the proposal as it stands is unworkable, but that you would support it if it was going to be include something else (that YOU want) that would make it massively expensive.