It's not unreasonable to be upset at not being able to afford food.
£30 for a fortnight is very tough especially at the moment, it's not sustainable.
You can be referred to the foodbanks that need referrals by CAB, by HVs etc.
I'm going to offer a few practical things because I don't want to not say them incase they help you or someone else but it is absolutely not saying you wouldn't be struggling if only you managed your poverty better - it is so fucking hard.
It's just sometimes people have been living like this a while and have cut everything down to the bone already so are on such low grocery budgets because it is all they have and sometimes if you've just been thrust into it you can be tight on money for food because your money has gone on other payments first because you haven't had time to adjust your budget for new circumstances.
The priority should be (in this order):
Groceries (you have to eat)
Basic Utilities (you have to be warm and be able to put the lights on)
Rent/Mortgage (you have to have a roof over your head)
Transport and Childcare (the costs of getting to work to pay for everything else)
Then e.g. Council Tax etc and other important bills where the consequences of not paying are severe. Unsecured debt comes bottom after all your essentials.
Citizens Advice can help with budgeting, advising about debt management, checking you are getting all the help you are entitled to, e.g. with childcare costs and including referral to the foodbank etc.
I'm not saying that it's easy to get appointments when you are working and absolutely poverty begets poverty in that if you have more margin in your life then you can make cost savings like the infamous electric bike but sometimes you just don't have enough money to save money.
It's also hard when you are unexpectedly pushed over the breadline because you may have payments for things that aren't essential and you wouldn't have chosen on your new budget but which you can't immediately cancel without penalty. Or a change like moving into cheaper accommodation has moving costs etc so you feel stuck.
I'm sorry that you are going through such a hard time, I have absolutely been there with the realising that I simply cannot afford something under £1 and it feeling awful.
You've nothing to be ashamed of. Not the poverty, not the emotional reaction to it. Nothing.