Here are a few ideas you may want to try to get the most out of your weekly food shop.
We understand that wastage is really frustrating and we want to help people avoid it as much as possible.
With fruit and vegetables you may find shopping in a fruit/veg shop gives you the ability to buy those smaller, more specific quantities. There will always be certain items that are sold in bundles, but shopping this way may minimise this problem.
Most supermarkets and deli's, sell cheese, olives, bacon etc, by the weight over the counter. Other dairy products may be best bought in the smallest tubs or containers available.
The reason the plan works is because you are eating the right amount of food, and it's healthy unprocessed food. If small changes need to be made to work around better usage of ingredients - like a vegetable substitution - this won’t impact negatively on the overall result. 
With this in mind, small changes like choosing a loose tomato over a punnet of cherry tomatoes, changing a green vegetable for another green vegetable you prefer, or using red or brown onion that you already have instead of spring onion, won’t have a detrimental effect on your plan.
With your meal plan recipes, the goal is always to make healthy, tasty, easy to prepare food. Your plan endeavours to create flavour and variety - hence not always using the same ingredients. Having said that, if you want to substitute similar vegetables to avoid wastage that is absolutely fine.
Another thing to keep in mind, is freezing food. This is an excellent way to avoid wastage. Canned goods like corn, chickpeas, tomato paste, kidney beans etc…can be removed from the can and kept in the freezer in an airtight container.
Most things can be frozen…even fresh herbs.
A good old google search will tell you the best way to freeze pretty much anything.
When you do freeze things, it’s useful to store it in quantities you often use. For example, meat in 100g lots, tomato paste in Tablespoon dollops…