What would be the visa requirements?

Hi I am going on holiday to China for 3 weeks in June 2017. I have details of my round trip f;ight and have booked a hotel for my first night in Beijing. I am going to pre - book a tour to Tibet by rail sleeper for the second day of the trip and stay in Lhasa for a couple of days. After that I want to travel by rail to as many places in China that I can either staying in rail sleepers or hotels booking as I go, what would the requirements be for such a trip?