The Tory argument on children's meals is that government provided an extra £9 billion to councils across the country to address the issue. The reason they did it this way is that there are children in need, that don't currently get free school meals who would otherwise fall outside the payment. Reasons for this appear to include families that see free school meals as a stigma and so won't engage. Councils know who these families are and can ensure the money goes to the right places.
The question I haven't been able to find an answer to, is why the government didn't just renew the scheme that applied over the summer, for half term and Christmas, and let councils deal with those in need that fall outside this. Hopefully all will become clear in due course