while I totally agree you will get far more bargains in aldi or lidl, than Tesco the problem is just going for a look when not used to it could lead you to impulse purchases, i'd suggest having a look at their websites first see what's the special offers this week etc and build a loose plan around that.
i'd also look at this as being a good opportunity to do a good freezer clear out, check cupboards and spend some time doing an inventory it might give you ideas for meals.
your husband might be a bit of a food snob but honestly the mince, chicken, meatballs etc are the same quality I find, in fact less fat in their meatballs to Tesco's ones.
There was a thread yesterday where a poster had 125 for food budget till much same date for 5 people, and some posters gave her links to recipes on bbc site etc where you made a family dinner for less than £5 see if you can locate it, there were some nice recipes.
Its hard the no sauce rule as id say most of my go too cheap dinners are all sauce based, casseroles, currys, dahl, chilli, thick soups for lunches, etc , but pasta you've already said is good idea so few cartons of passata and you can make all sorts of different home made sauces, throw in some aldi meatballs or chorizo for a meaty one, or peppers and olives for veggie one.
For other none sauce dinners, my teen likes meals like egg, beans and home made chips or sweet potatoes done as wedges in oven are a hit. She loves noodles so lots of stir fries- would this fall foul of the no sauce rule?