I think the key is in your question: "I am on a diet at the moment". Diets do not work. Life time changes do. You need to stop punishing yourself with strict regimes and work out a plan where you can eat what your body sraves but still be healthy.
My advice is to eat 3 meals a day. That way you will really appreciate each meal. ie- no snacks except fruit. The sugar in the fruit will keep your sugar craving at bay. Fill your plate with salad and/or veg, and hence the rest of the plate can be used for the normal food. This way you naturally restrict your intake and reduce your calories but you are still eating healthily.
VARY what you eat. Eat different food every day. But eat half the amount you WANT to. Most of the time you will be perfectly content after eating a smaller amount. Our bodies need surprisingly little food to function well and we all eat way too much quantity.
Regarding the cravings, EAT what your body is asking for, but much smaller amounts. Also, make a VERSION which is lower in calories. Eg- fish from a supermarket and a handful of chips cooked at home with a big salad is just as nice as chips from the chippy, but far better for you.
he only thing I would say to avoid is chocolate. It really mucks up your hunger and sugar signals, and is so addictive- ie- once you have some, your palatte gets a taste for it and wants more! Then it is hard to shake. Stay away from it and your palatte will soon change. You'll soon be craving veggies! Buy a bar of fine, dark choc and have a square of that with a cup of tea in the evenings if you fancy it. It will be just enough- honest! Also "Options" hot choc drinks are nice if you really crave chocolate.