If you can't afford food in the short term, yes to a food bank referral.
Longer term you have to look at your overall budget to see what the problem is and get ideas as to how to solve it.
If you have maternity allowance, UC and your partner's income, you should be able to afford the basics unless your rent is very high or you are in debt.
Although you might not be able to do things that cost money if you have seen a drop in income, so you'll have to see what you can do that's free or cheap to 'enjoy yourselves'.
Moneysavingexpert is a great resource. Look at the money makeover to comprehensively review your budget to make sure you're getting all the benefits you're entitled to and to cut costs where you can.
This, along with tips to make a little extra money here and there, eg switching your bank account to get a free £100, means that you can up your disposable income by a noticeable amount. Plus, if you're in debt, there's signposting to where to get the best help whether you just need to cut back, or might possibly need a more formal solution.
www.moneysavingexpert.com/family/money-help/
Of course, if you find that you really don't have enough money for the basics, you'll have to see what big changes you can make such as moving somewhere cheaper, going back to work sooner than you would like to, or can your partner earn more?