How late does the bus from Gubei back to Beijing run? Is there a bus back after 22:30?

For the return trip, you can take bus line Mi 51 to Miyun Bus Station from Simatai Village at the water town. Then, change to bus line 980 or 980 Express to Dongzhimen Station in downtown Beijing. The last bus of Mi 51 departs at 17:30; the last bus of 980 departs at 19:00; the last bus line 980 Express departs at 18:30. I am sorry that no bus is available after 22:30.

Yes, there are many hotels and hostels at the water town. Just walk in and check in. May you have a nice trip! :)