I think that of the known worldwide brands, the only diet drink available here is diet coke,zero coke, pepsi max etc. You can buy some sugar free Turkish brands, but I do not think they are comparable to the sugar free drinks available in the UK. Unless you are diabetic, when obviously it is vital to have sugar free drinks, does it really matter to have a few extra calories whilst on your holiday? Afraid if the answer is yes, diet coke is your only option.....