BBC Good Food also do a great magazine that I look forward to every month. Reasonable portion sizes and they even have a feature where they give you ideas what to do with the leftovers some of the recipes generate.The bbc good food website is so good for learning to cook there are some fab recipe collections (they’re listed by dietary requirements, season, ingredient, cooking time, difficulty rating etc) and the search function is really good. The more you cook the more you know the basics of how dishes are put together, the more adventurous you get.
You said you’re funny with freezing some foods, and portion sizes. Most recipe will make 4 portions, so half the ingredients, make 2 portions and put the other one in the freezer for the next day? Means you only have to cook once for 2 days and you don’t have to worry about the freezer.
Olive is another great British magazine. I have a Readly subscription and have fallen into an abyss of British cooking magazines, many of them are much, much nicer than German ones.
BudgetBytes is a good blog for this as well. It's based in the US, and some things aren't available here, but the founder generally creates recipes with normal grocery items, is huge on leftovers and not wasting anything. Too many recipes with a ton of garlic in it (yuck for me), but still a nice blog!