layover 1hr 45

I’m flying from Heathrow to Bangkok with airchina, with a 1hr 45min layover in Beijing. I’m just wondering the process and documents I’d need, as from what I’ve read, it’s going to be tight. Is it simply plane to plane or is customs necessary + health form or do I still need to fingerprint.

Also what is "The application for a preliminary entry permit" that i need to apply for? just wondering as of course the layover time is tight