Hi OP. Well done on taking the first step to changing your life - that takes guts on its own! I'm not sure whether I can help you in anyway but I'll try...
Food
This is the most important factor. You have to run for 15 hours to burn off a chocolate bar... well maybe not 15 but a lot... so all the exercise in the world won't help if you're eating badly.
Please please don't go on a "diet". Its only temporary and, as soon as you start eating the old food, you'll put the weight back on, having learnt nothing. Avoid meal replacement diets especially - you need to eat nutritious food not shakes!
I would second the advice about MFP. If you're recording it all, you're accountable. Aim for 40% protein, 40% carbs and 20% fat. 1200 calories. Scan food before you put it in your shopping trolley.
Preparation is the key. It's easy to eat crap when you're busy - a sandwich from the shop, a pizza chucked in the oven. Get the tupperware out and spend one evening preparing your meals for the week. Then you can just grab one out of the fridge whenever needed.
If you struggle to change eating habits, work on one meal at a time. In the first week, try to get breakfast right. Ditch the cereal and toast for overnight oats (40g porridge oats soaked overnight in almond milk, add dried fruit, blueberries, cinnamon, whatever you fancy) or an egg (use cartons of egg whites for scrambled).
The following week, get lunch on track by replacing sandwiches with colourful salads and vegetables. Include good fats like avocado and nuts but keep them small. Humus and crudites. Fruit and yogurt. So much choice!
Once you've got breakfast and lunch down, work on dinner. Check your portion control / plate size. Try to stay away from carb loaded dinners like shepherd's pie, and try fish with lots of veg. Turkey is low fat.
Snacks - bin all the chocolate! If you really have to have something sweet, try Fulfil or Carbkilla bars.
Drinks
Try to drink LOADS of water, a glass with each meal and throughout the day. Ice water with a slice of lemon if that helps. Avoid fizzy drinks and alcohol.
Exercise
Running can be bad for you if you're not in shape. A brisk walk can be just as beneficial. Personally, I hate all that HIIT jumping around bollocks, so I would recommend resistance training - push ups, lunges, squats, crunches. You can do it at home with no equipment and take the exercise down a level depending on ability e.g. start with push ups on your knees.
Pick a regular time for exercise and stick to it. Consistently. Half an hour a few times a week is enough. Get up earlier if need be!
Every lb of muscle on your body burns 100 calories a day just sitting there. Every lb of fat burns 5. Swap one for the other. Don't aim for just fat loss, aim to build muscle too.
Motivation
You want to lose weight. Tell yourself you can. Put a picture on the fridge of how you want to look - it could be someone else or an old pic of you. Read all the cheesy motivational memes on Facebook. Watch Nike motivational videos when you feel like skipping the exercise.
Tell your family and friends that it is important to you. Surround yourself with supportive people who won't tempt you to have "just one cake"
If it goes wrong, forgive yourself and get back on it. If you had a puncture, you wouldn't slash the other tyres, would you? Fix it and start again.
I'd be happy to email you some recipe plans and exercise videos that i use, if you want to PM me. I've lost over 2 stone this year so have some insight, although I'm not a personal trainer by any means!
You've totally got this! Go out there and smash it! xx