Notacs, even if you have saving etc, if you can't access them, or if your DH would make this difficult for you in some way, you can still claim benefits I think. For example, a person who has sold their house, and needs to rent somewhere temporarily could still be entitled to housing benefit, as the amount from the sale is earmarked to buy a new home.
I think you need to get some actual, real, advice from the DWP and the Tax Credits about what you actually would be entitled to.
You should also contact Womens Aid, as they can help you with these practical details.
I get the feeling you are a bit Rabbit-in headlights , understandably, and focusing on the wrong things.
Of course you will go back to work, when you are ready, and you will earn what you are qualified, and eventually support both your children as a lone parent. In the mean time, there is a lot of help, financial and otherwise, that nothing, actually, is stopping you from accessing.