While it's a very good thing to have a will for admin reasons, and to know what your access to immediate cash would be in the event of your husband's death, I don't think you need to be too terrified of the intestacy situation.
His half of the house goes to you automatically.
Life insurance to pay off the mortgage goes to you automatically.
Death in service benefit goes to you automatically.
The contents of the joint bills account goes to you automatically - I know you said that's not much.
Any benefit related to a pension plan would go to you automatically.
Government Bereavement allowance goes to you automatically.
Then you look at what's left, which would normally be his personal possessions, his current account and his savings account. If those items, and only those items, are less than 270,000 then it all goes to you. If it's more than that, then the excess is split between you and the children. So if he had £300,000 in savings, or maybe a holiday home in his name only, then you'd get 270,000, plus half of £30,000 ie £285,000, and the children would get £15,000 between them.