You can quite easily break the cycle of craving sugar-eating it-and craving more! One of the big keys is to add protein to every meal! This automatically makes your diet lower GI. Protein slows down the digestion process which means you will feel full longer and you won't have fluctuations in your blood sugar levels. What happens when you eat sugar is that you get a sudden energy spike only to have a huge drop at the other end, this makes you then crave more sugar to get your energy levels up again and so on.... If you have to have something sweet then make sure you are also eating some protein with it so that the sugar doesn't hit your blood stream quite so quickly.
If you want to follow an actual diet plan, which I don't hugely recommend because most people set themselves up for failure, then i would go for a Low GI or a Low Carb diet - but not no-carb like Atkins!!!
The other big key to breaking the sugar craving cycle is eating nutritious food! Your body needs a certain number of nutrients to function properly, if you are eating mainly processed or junk foods your body will crave more and more food in order just to get its daily requirement of vitamins and minerals. So eat what you should before what you would! Eat the lean protein, complex carbs and vegies vegies vegies first, and then allow yourself a treat if you still feel like one.
If sweet things are your main problem you could also try substituting the unhealthy snacks with some healthier options. There are many great chocolate covered protein bars on the market. Even the Atkins ones are great. You can also buy yourself some low calorie, chocolate (or whichever flavor u like) flavored protein powder and make a milk shake with it by adding frozen yogurt and some ice-cubes. If you have one of those ice crusher blenders and only put a little fluid in it ends up turning out like chocolate ice-cream because the protein powder thickens the mixture. I actually freeze bananas and put them in my shake (make sure u peel them before u freeze!).
I would go online and use a calculator to work out your weight loss calorie level and then devise a high protein meal plan that uses the sort of foods you find easy to buy, prepare and eat. You don't need to make huge changes to lose weight, you just need to be consistent and slowly form the healthy habits.
Oh, and lastly (sorry if i am going on a bit), exercise!!!! I don't know if u r already exercising, but that is a huge key to long term weight management. If u can't afford a gym membership and doing like boring walking, then get yourself some fun workout DVDs to do at home. I have a huge collection and I actually look forward to doing them every morning. I have my favorite instructors and use a new one nearly every day of the month so that i don't get bored. It really works because its like having ur own personal trainer at home and u can find a routine that really works for u.