I have had some success since diagnosis and my diet has changed to LCHF. However, I do not restrict myself when I go out for a meal or a family celebration. I try to make better choices, such as a mixed grill, but I will have the chips. Once a month or so I will have a kebab or pizza when the family gets a take-away and I do test regularly.
For me the odd day here and there does not negatively impact my overall results. I think what people here have said is right though, it's the getting started that can be hard. For me I did things in small steps, for example I started by changing mainly my breakfasts and then included lunch and worked up to dinner.
Snack wise, almonds are my go to and there are studies that show a small amount of almonds after a meal can contribute to lowering spikes. In terms of chocolate I have two squares of Lindt 90% per day, usually with almonds as it tastes great. I made the mistake on holiday in June of buying some Lindt 99%. That's full on! However when I got back my 90% tasted like Cadburys by comparison. Lol!
Defo get a meter and test, that way you can figure out the foods you can enjoy. Also there are some great alternatives available cheaply. I buy green rice from Iceland that takes 3 minutes in the microwave. It is broccoli, kale, spinach, sewaeed and cauliflower blitzed up. If I have a curry I have it with green rice and it tastes the same as for me rice is just there for texture. Come to think of it I don't know anyone that 'enjoys' white rice as more than filler.
Morrisons sell a ready meal that I use for lunch some days called Eat Smart Counted Roast Chicken Dinner. It's chicken in gravy with carrots, peas and 3 new potatoes. It comes with a stuffing ball but I bin that. The whole thing (including stuffing ball) is 15g carbs. It scratches a potato itch and I cover all the veg in butter to make it extra tasty. My BS goes up 1 mmol after 2 hours. Worth checking out if you can.