However, recently, I was rejected for more than one job without interview which has knocked my confidence
Welcome to the real world!
You sound quite spoilt, actually. And no way should you use your children's money to ease up some of the hard lifestyle decisions you & your DH need to make. You and your DH need to have a serious discussion about money, budgets, and ways & means.
If your job is managing the household, then you must be doing the budgets, of course, aren't you? So you should know where the money is going and where it's possible to cut back.
And in the 5 hours a day your DC are at school, you can also do some research: find out about after-school care: clubs, an after-school nanny share, or the like. Cost it up. Present it to your husband in terms of overall family budgets. His salary, your salary, etc etc. Add in HIS inheritance (don't DARE touch your DCs' money), and look at all the possibilities.
Then have a look at reasonable jobs you can apply for & are qualified for.
Because of your confidence got a knock by not being short-listed for a job, you really need to think about why. Sadly, women taking time out of paid work leads to a perceived diminishing of their skills,. It's why you should never give up your job (very sound advice given to me in my 20s).
You need to get back into the paid workforce soon, so you may as well start now. Then you can start to catch up on pension & so on. I also happen to think (my personal opinion) that staying at home for longer than primary ages of DC is bad for the SAHP's mental health, and I've also seen it lead to tensions in marriages - sometimes irresolvable.
Your planning should look at all the possibilities in a very financial way; add in yours and his feelings about who works at what afterwards.
And think about the enduring stress & pressure on your DH always to be the only or main earner because you don't want to get back into the paid workforce. That's a strain/tension on your marriage you really don't want to risk, IME.