Going back to the gym and don’t know where to start…
Are you just recently going back to the gym? I suggest focusing on the basics. After your cardio work, go find some space and do a few sets of Pushups (from your knees), Crunches, Back extensions (laying on your stomach, lifting your hands and feet up at the same time, holding it, then down is one), Lunges, and Squats. Go for a minute for each. Record how many of each you can do (with good form!) and try to break your record.
Do 1 set, then the next day, maybe only do 2 or 3. Then the next time, go all the way through. Repeat.
BUT FIRST….you have to commit. Commit not to the scale, but to your body. Then, and only then, can discipline take over and make working out a staple in your world. As far as eating, you seem busy, so PLAN! Accept that you dont have time to cook all the time, but prepare for those times a day or 3 in advance.
My advice only works in practice. If you do nothing, you will not see any changes.