In Beijing 5th - 7th October 2014

Have just found out about Golden Week. We are arriving in Beijing late Oct 5th, want to visit the Great Wall on the 6th and get to the port early afternoon (by fast train) on the 7th for an evening departure on a cruise boat. Would it be best to organise the tour to the Geat Wall before we leave (Australia)? - and the best tour? ..and can you pre book trains?. Tks. Michael