Second shopping around and tweaking what you buy. Beef has suddenly got very expensive, so use turkey or pork mince instead, also add in pulses. When I make chilli, it's a pack of mince, two or three tins of beans, same of tomatoes, pepper and onions to make a big batch for the freezer.
Healthier to cook like that too. Bolognese always includes lentils, I sometimes use a can of green lentils, it's not necessarily for cost, more health and environmental reasons, but it's also a bonus that it's cheaper.
Pork is often the cheapest meat for a roast, use the leftovers for tacos and to add to noodle dishes.
Use seasonal veg and cheaper versions eg carrots, normal broccoli instead of sprouting, cheapest cabbage like a PP said.
Where do you buy your corned beef? A tin of John West or Princes from most supermarkets is nearly £4 but last time I bought it from Aldi, it was about £2, also if you can go to Costco, a 12 pack was £25. It's sometimes also cheaper in places like Farm Foods.
As far as I can tell, it's all exactly the same because I think it is made in bulk in South America and sold to suppliers across the world to put into small cans. In the past I've bought value corned beef and I compared the nutrition and ingredients with different types and it was all the same.