Love Food Hate Waste is a good place to start: “The average family of four can save as much as £70 per month by reducing their food waste. This can come from buying only what you need, storing your food properly, and eating everything you buy... We believe that every person has a part to play in reducing food waste and looking after the planet. The time is now, and the answer is simple: love food, hate waste.”
The website has tons of good advice about planning meals and shopping, cooking and recipes, storage and keeping food fresh, including on getting to know your freezer, where you can store a lot of left-over foodstuffs, including some surprises (you can freeze butter, cheese, cooked chips...).
TTK has supported cookery workshops in the past because, if you can cook, or make soup, you need never throw away food. But YouTube has how-to videos on almost all kinds of cooking if you need ideas or advice – just search by ingredient.
BBC Good Food is also an excellent source of recipes and advice.
Our top tip for disappointing fruit – don’t throw it away, cook it! Remove the seed, slice it up if necessary, and cook it briefly (boil, bake or use the microwave), which releases the fruit sugars with a transformative effect – works a treat on woolly peaches or tasteless apricots, even on over-ripe fruit!
See also the Abundance project if you have fruit harvests going to waste.