What to eat and when to do it?

This is a multi-billion dollar question. BUT, it isn't as complicated as many want you to think, period! You need to eat three meals a day, breakfast, lunch and supper. Additionally you eat 1-3 snacks. You might say, I can't eat anything in the morning, then I suggest start small with maybe two spoons of yogurt for a week and then you add a spoon each week until you eat a full breakfast. 
Breakfast, I have eaten oat porridge for the last 40 years with a handful annual exemptions when I eat pancakes.  A bowl of porridge and I wrap it up with a piece of bread and a cup of coffee. If I would eat based on what I think is tasty it would be close to a dozen pancakes with maple sirup, or bacon and eggs, or giant bowl of corm flakes with sugar. Those alternatives aren't healthy to eat on a daily basis. to get you something to look forward to you could it a less healthy breakfast during the weekend. I tell my clients to keep a 80% good diets, that's good enough for most people.  
Breakfast 06:00-08:00
Oat porridge with raisins or cranberries or a small moshed banana or table spoon of apple sauce or similar, 
Unsweetened yogurt with some fruit or less sugary granola. 
A smoothy 
Cereal which isn't sweet, less that 15% sugar content. 
Lunch 11:00-13:00
A descent sized tuna sandwich. Fish with rice. Meat with potatoes. And a salad with those meals..Doesn't need to be anything fancy. Cut a pepper or a tomato.
Or vegetarian or vegan alternatives. Those are only couple of examples .The key thing is not to eat meals containing plenty of sugar and fat. If you don't prepare it your self you don't know how fat and sweet it is. 
Supper 06:00-19:30
It could like lunch. Our family usually eats a warm meal a day. Other's two. Personally, I think that creates a lot of extra work for the person in charge of the cooking.
Soup, with bread and salad. Unsweetened yogurt with fruit or/and some homemade granola (very easy to make) or nuts. and salad with a piece of bread. A salad with cottage cheese. Vegetarian or vegan alternative. 
Snacks:
Personally, I usually ave one snack between lunch and supper. This if I work from home. If working outside the home I usually have a snack between breakfast and lunch as well. I could be a handful of nuts or/and couple of table spoons of cottage cheese. An apple and cracker with natural unsweetened peanut butter.
The key is to sync your eating with your physical activity. As you are very well aware of you feel hungrier if you work in the garden for three hours comparing with sitting behind the computer. Learn to differ between being hungry and having a cravings. A good rule is not to eat about three hours before you go to bed. 
One school of thought recommend intermittent fast, meaning that you eat two meals and then you fast for 14-16 hours. According to the supporters this should give you health benefits. I can't tell you to do this or stay way from it. I don't know enough about it. If you like read more about it go to mercola.com and search for intermittent fasting. 
                            -Chris  IronCouch.com