When you say you waste a lot what do you mean? Because it's relatively easy not to waste.
I write down what I spend everyday, when I added up what I spent on parking and shop bought sandwiches in a month it came to £50. I don't even work full time. I take a baguette most days and it's sooo cheap to have a really nice lunch. I park in side streets when I go into town for free and get everything done in 30 mins.
If you haven't tried Aldi I would advise going, I used to think I would never go there but now we do and apart from the steak the food has been really good.
If you have a farmers Market/shop nearby then use it! Our potatoes only cost 60p for 5lbs, they are £2 in tescos.
We use sainsbos basics tea bags, they cost 33p for 80 and Dh still comments how nice our PG Tips tea is as I haven't told him that we have changed brand (15 months ago).
If you have a coffee addiction then a flask and a good ground coffee would be so much cheaper.
If you get a breadmaker get a panasonic one, they are really good.
I used to use basics/smartprice oats and golden syrup for flapjacks, very cheap but delicious.
If you replace any lightbulbs need replacing then the LED ones are comng down in price and use so little electric, lighting and heating make up most of your electric and gas bills.