Tianjin Nankai District to Beijing Airport

Next week, I must go to the Airport in Beijing. The airplane will leave at 1.55 in the night. So what is the best way to get there. If I take the Shuttle bus from TJ to Beiijing airport, I will be there at 9 in the evening. Because the last bus runs at 18.30, right? Do you think I should take the bullet train to bejing south? Is is difficult from there to find the subway to the airport and is there a subway line who goes to the terminal 2? And is it also possible to leave TJ at 9 or 10 that I can be at the airport at 12? Sorry for so much questions and thank you in advance.