Cut out a load of processed food and ready meals. It's amazing how much you save there and healthier too.
Also look at supermarket own brands. MUCH cheaper than named brands and most have less addatives, colour and sugar in them too. Yes they might not last as long unless tinned but you'll be saving money and eating healthier at same time.
When really struggling I lived off pasta. Can get huge bags for £3 now that last months. Pasta bakes, pasta salads, spaghetti bolangse, home made lasgne etc or even just pasta with veg and gravy.
Buy big packs of frozen veg - lasts much longer than fresh especially in this heat. Only stuff you cna't get frozen is lettuce but you can grow potatos, lettuce and carrots at home in pots (better still in the main part of garden) unfortunatly that is weather dependant and you might not get a crop like this year only our spuds have grown. Last year we also had carrots, lettuce, onions and sweetcorn which saved use about £20 a month.
For warm weather then sandwhiches, beans on toast/cheese on toast and salads are all good. Winter then bring out the stew pot! Chicken stew and dumplings (make dumplings yourself) can last 2 people 2 days if you use chicken thighs (which taste really nice when slow cooked) Soups are also nice fillers if you have homemade bread rolls with them.
For peoples OH that demand some junk food to take to work for dinner etc then bake your own cakes or get supermarket brands etc Hubby loves his mini apple pies to go with his sarnies and kept getting Mr Kipling ones at £2 a box, I swapped to sainsburys own for 49p and he likes them better and we save money
If you live on bottled water stop buying them and get a water filter jug instead. At first I would only have bottled water as we live in a very hard water area and limescale is bad. Cost us at least £20 a week as used it for pets too. Water filter cost use £20 (comes with 1 filter) and a pack of 3 filters cost £10 giving us a endless supply of fresh tap water for £30 for 4 months then £10 every 3 months after
Hope this helps hun. It's what got us out of the creek when hubby was made redundant and without a job for a few months