The Sphagnum key covers all British species apart from a few rarer ones while 260 other moss species are currently included in the Moss key. Both keys concentrate on field characters though include some microscope characters to aid identification.
A Liverworts key is currently in development.
You can find the keys on Lyn’s website at https://visual-flora.org.uk/Mosses-liverworts/Mosses-liverworts.html. Please contact him directly at email@example.com with any queries or feedback.