Advice pages from Oxford's Department of Education can be found here. This document is intended to summarise suggestions and resources for people to move face-to-face teaching to an online format.
Higher Education e-learning sessions are available here (useful for spotting students at risk).
Miller, Michelle D. 2014. Minds Online: Teaching Effectively with Technology. Cambridge, MA: Harvard University Press.
Baran, Evrim, Ana Paula Correia, and Ann Thompson. 2011. “Transforming Online Teaching Practice: Critical Analysis of the Literature on the Roles and Competencies of Online Teachers.” Distance Education 32 (3): 421–39. https://doi.org/10.1080/01587919.2011.610293.
Both of the above are currently available through SOLO.
The following (free) online courses are also recommended:
The University of South Wales, 'Learning to Teach Online', on Coursera. https://www.coursera.org/learn/teach-online#faq
Open University on ’Taking your teaching online’