Congrats on your decision to be healthier! While it can be hard to get into the routine, it will become second nature as you feel better and get stronger.
I'm not a nutritionist, but I hope this will be helpful!
First, there are certainly a lot of great options out there than coke! Personally, I really love Kombucha and I'll chose it any day over coke. Instead of dehydrating you, you actually improve your gut health and hydration. KeVita Master Brew is one I recommend if you haven't had it before. A personal favorite :)
Also, I'll cut up mint leaves, strawberries, lemon, etc to a pitcher and keep it filled to have more options without extra sweeteners. Frozen or fresh are fine options. I like to use local honey (helps with allergies!) to sweeten things or RAW sugar.
And if you enjoy coffee, you should give tea a try some mornings off and on. ( I can't give up coffee, yum!) Quick meals can be a wheat toasted english muffin with almond butter and mix berry spread. Banana and yogurt. Multigrain waffle, banana, and peanut butter... get creative but make it count!
Secondly, keep fruit nearby and try to avoid junk food. You'll feel more inclined to eat tasty things like grapes or orange slices rather than chips or gummy worms. Especially when you have the munchies! ;D
Thirdly, it's never a bad time to learn how to cook! Highly recommend. You can control the amount salt,sugar,etc going into your meal. Rice cookers and crock pots are great options if you have to step away. Meal prepping can be as simple or extensive as you'd like it to be. You can cook your lunch/dinner for the entire week. Breading or marinating can provide quick and ready meals.
I wish you luck on your journey! If you can squeeze in at least 1 hour of workout at least 3-4 days, you'll feel great before you know it. Be realistic with your goals and don't be afraid to have "cheat" meals every now and then. You got this!