Look at every product you buy and consider if there's a cheap version, ie buy shops own instead of a brand, could you have a similar meal a bit cheaper. Check if there are any wines on offer or clearance and buy those if cheaper, I just bought a clearance Finest bottle of white for £4. If DH is veggie, it might also be easier having a few nights where you all eat the same, veggie fajitas, veggie chilli, veg spag bol, macaroni cheese etc. I often make a tomato sauce and just through in whatever other veggies or protein we need to use up.
Also, make sure you don't waste anything. Leftovers can be eaten by one for lunch or served as a side dish the next day.
Our food bill is really low - £45/50 a week for food, this includes all lunches, dinners etc. Toiletries and cleaning products are on top and I buy in town at places like Savers, Poundland, Superdrug as cheaper. So over the last week we've eaten:
Breakfast: cereal, porridge or toast if one of us wants a change
Snacks - aways 1-2 pieces of fruit (bought in bags for 69p), biscuits, cake or fruit, occasionally toast, DD has had one packet of crisps and I've had nuts once
Lunch - sandwiches and fruit for DH/DD. I often have something with salad. Also, DD has biscuits as well as two other things, something like veggie sticks, cereal bar, babybel, the odd packet of crisps or mini choc treat.
Main meals this week have been:
Frittata - I added onion, tomato, broccoli, potato to this - all items I was using up.
Bean chilli with rice
Veg curry (with chickpeas added for protein), rice and naan bread
Chicken, potatoes, carrots and peas
Creamy tomato pasta with cheese, carrots and broccoli
Veggie casserole (with butterbeans) for us, SF chicken, potatoes, carrots and peas for DD
Tonight - Tesco value white fish with homemade sauce, potatoes, parsnips, carrots and sprouts
Tomorrow - only two of us so I may have a jacket potato with beans and cheese which really fills me up, DD may have fish in breadcrumbs with veggies.
We don't bother too much with desserts, yogurts are always on offer. DD will often have another piece of fruit later on and sometimes we have protein bars.