Only three of these sentences have this meaning, while two of them have a different meaning, I will see you in two weeks' time. I will see you two weeks from now. I will see you in two weeks. These three sentences all have the same meaning. I'd presume that we'd meet again on Monday 23rd March. I will see you the week after next. This is less precise. It would mean that I'll see you some time during the week of the 23 - 30 March. I will see you in the next two weeks. This means that I'll see you some time during the next two weeks - any day between now and 23rd March.

Best options : "I will see you in (exactly) two week's time" If I say this today, I will see you on exactly 23 March or around 23 March. "I have worked / I will work for 2 weeks" - use for + duration