Where to get information on Nutrition

Good sources suggested above! I'd add the the nutritional advice from mainstream national/international bodies is also quite good: USDA, NHS, WHO, etc. Many people have an oversimplified understanding of what those resources offer, kind of the "glance at page 1" view. If you take a look at their sites, the actual information is much more comprehensive and nuanced than that cartoon-like understanding. I'm most familiar with the US version, which is here:

https://www.myplate.gov/myplate-plan

There are also sites like this one (with which I'm not affiliated, BTW) that will recommend full eating plans in various styles, with recipes:

https://www.eatthismuch.com/

One thing to consider is that "convenience foods" is not necessarily a full synonym for "fattening unhealthy foods". If you look around, you can find convenience foods that are calorie efficient, and nutrient dense. That can be anything from frozen meals, to bagged salads, to frozen vegetable mixes with some light seasoning/sauce that you can combine with rotisserie chick, or packet chicken/tuna or some other simple protein source to make a full meal. Reading labels, and taking some time to look at areas in the grocery store you're skipping now, can help you find these.

Fresh foods are great, but many frozen foods (and some canned) these days, are nutrient-dense and tasty.

In addition, if budget isn't super tight, some people benefit from signing up for one of the services that delivers healthy meal ingredients you can cook yourself, with some of the prep done for you. That can introduce new foods/recipes/techniques in a manageable way. It's possible to sign up for a small number of meals per week (with some), it's not necessarily a big deal where you have to sign up for all meals for a week.

I'll suggest the Volumetrics Diet Plan...it emphasizes eating vegetables/fruit...low cal, high nutrient density foods. Here's a review of it: https://www.healthline.com/nutrition/volumetrics-diet

Meal delivery kits are a good starting point (I tried Hello Fresh, but it's only convenient in the sense that the recipes and ingredients are selected and delivered and you pay a premium for that...it's a lot more expensive than just putting it together yourself.......I still had to do all the chopping and the cooking and I wasn't impressed by the meat quality (I had food textures with their meat that I generally didn't even with Kroger budget meat) so I actually switched to the veggie plan) but unless you plan to use them the rest of your life, you'll probably want to learn to cook healthy on your own.

I’d be careful going off what government agencies say, as they get lobbied pretty heavily. Honestly, I just focus on eating mainly unprocessed stuff. Whether it’s beef, eggs, dairy, vegetables, fruit.. if all that’s done to it is stuff like pasteurization or whatever then I’m fine with it. There’s just way too much conflicting information out there that is impossible to wade through