Forget the groceries and stock up on things that you like to have but might not be able to afford later. I'm thinking of stuff for hobbies (wool, fabric, paints, brushes etc), cosmetics, books, perfume, perhaps a winter coat? As someone above says, the supermarkets are always full of special offers on household stuff, so no real need to stockpile that. By the way, are you near a Lidl or an Aldi? I've found you really can save money there. (Oh dear, does that count as advertising?)
Stansgran - I had to laugh at your DH 'taking over the shopping' as my DH has turned out just the same and, like yours, queries many a purchase. You do see an awful lot of older couples falling out over the supermarket shopping, I've noticed. DH is particularly fussy about buying fruit and has a worrying habit of loudly comparing prices with other supermarkets to the detriment of the supermarket we are currently standing in. He has not quite yet taken to telling other customers where you can buy bananas more cheaply but I can see it coming.