I am trying to translate this sentence: "Service charges are excluded but you only need to pay this if you will eat in restaurants."
Is this an appropriate translation: "Serviceavgifter er ikke inkludert men du må kun betale det om vil du spise i restauranter." ?
Well done! Replace det with either the object pronoun dem (the subject is serviceavgifter - de) or disse (=these), and you have a perfectly valid translation.
In written form I would also add a comma after inkludert, but don't worry too much about that unless you feel ready for some real pickiness.