Complex sentence: Sarff takes the Doctor, Clara and Missy to a supposed hospital in space and while the Doctor is taken to Davros, Missy, still with Clara, notices the gravity doesn't feel artificial, as it would be on a space statin.
Split into simpler sentences: Sarff takes the Doctor, Clara and Missy to what appears to be a hospital on a space station. Whilst the Doctor is taken to Davros, Missy, still with Clara, notices the gravity doesn't feel artificial, as it would be on a space statin.