Am about to start the diet and normally prefer to cook with groundnut rather than olive oil, is this acceptable and will it make any difference to my progress if I do not use olive oil?

It shouldn’t hinder you at all as long as you count the calories in what you are using. There are no ‘magic’ foods on this diet, just the need to get nutrients from the three food groups of protein, low-carbs (fruit/veg) and fats. Your ground nut oil will help with your healthy fats and provide you with other nutrients not found in olive oil.

It’s always a balance with oils. I use coconut oil, olive oil, butter or nothing depending on the dish. Just remember that the oil helps the flavor profile of your dish.