Not as far as I know, but you'll get some of her standard rate band and also a home carer's tax credit worth 810 p.a. So I calculate there'll be a net household income of 680 a week, compared to 1,083 if she stays working.
That's a drop of 403 per week. If she stays working though you say your childminding cost goes up to 200, so by her taking the redundancy you're only worse off by 203 a week. And her redundancy will clear the credit union loan, so then you're only worse off by 83 a week. Presumably there's some other costs associated with her working, such as petrol cost if she has any kind of a commute at all, that will also fall.
You might find it's not costing ye all that much at all, and she might really value getting to bring up the kids for a few years, I know my OH and I would love to be able to afford that.