Free school meals are a solution to a problem that's been misidentified.
It has to start with school.
Proper sex education not just the science. Don't give the fluffy cute baby pictures, talk about being puked over, not having a moments peace, the lack of sleep - the fact if you're a decent parent the worry never ends.
Talk about benefits - the physical cash, it's not enough to live comfortably unless everything you own is higher purchase. Talk about a future career, be honest, if you've got a nipper and with no track record it's minimum wage jobs because employers never know when the kid will be ill, when you'll get called to school without notice etc etc.
Instead of fluffy RE and the rest of the nonsense, actually educate the kids properly with lessons that will help their lives rather than stuff that's only useful down the line if they burrow down in maths, science, tech etc....get proper cookery and house management and budget subjects instead.
Teach them sensible stuff. Fresh or frozen might be a bit more expensive in some cases compared to that microwave burger, but you see, you can get more than 1 meal from it with planning.
A desperate dan, some curries, stews etc...portion it off and you can get multiple meals from that (so it works out cheaper over all because you've spent 20 minutes off your backside).
And when things are tight, you aren't 'entitled' to luxuries - prioritise.