Is there anything you like from eating chocolate and crisps, such as sweetness, texture, flavor? You can find healthier alternatives to those food. Say instead of milk chocolate for example, switch to dark chocolate. Instead of crisps, try something like popcorn (not the microwaved versions) or carrots.
But otherwise, the simplest advice I can offer is to start slow! Personally, I was raised to have a very bad diet and due to personal circumstances, I fell into a bunch of cycles of binging, starving, etc. All in all, horrible relationship with food until I decided to turn that around last May, and I've lost 13 kgs so far (I think that's like 2 stones according to Google). So start going for slightly healthier alternatives first (like the ones I mentioned above), then gradually keep moving onto food that will nourish you which you will eventually like.
Also try exercising! It may be difficult at first, so try something you like, such as a sport, or maybe go for walks outside. Or if you (like to) play video games, you could try playing games on the Wii or Kinect if you own them, or play Just Dance Now using your phone and a screen like your laptop (note that you can only play 2 songs every 24 hours ). Just make sure you do something you enjoy because you'll really feel good at the end and it'll turn into a routine.
For cooking, try finding recipes you've always wanted to try/eat. Imo it doesn't really matter much what it is (at first at least) because it's way better than eating outside or buying processed/packaged foods. Saves money too! As a suggestion try eating foods with protein or fiber (so like meat,eggs, tofu or fruits, green/leafy veggies) as it keeps you fuller for longer.
As for binging, as I mentioned I struggled with that too. It's difficult...but for me it was due to circumstances. So make sure you take care of your mental health if you're stressed or going through a rough time! (Try meditation perhaps?). If it's not due to any emotions, then maybe try tracking your calories with apps like MyFitnessPal so you could be more mindful. (Unless if you have suffered from an eating disorder then I would advise against this method as it involves calorie restriction)
Also one thing that really helped me change my perspective of food is educating myself in nutrition. Watched a couple of documentaries regarding fast food and high carb diets, as well as videos by a couple of YouTube channels. It really helped me understand what junk food does to my body and what are the consequences, so I became a lot more mindful ever since.
Lastly, don't beat yourself up. You will probably have days where you want to give up. You will probably have days where you fall off the wagon and binge (this has happened to me and many others on their weight loss journey as well). But your future self will thank you for your efforts! It's perfectly okay to eat chocolate and things you generally like (I still like eating biscuits from time to time!) . Moderation is key to everything, so that also means don't get too obsessive with working out or dieting, you might harm yourself instead. I wish you all the very best, you can do it! <3