Welcome to the safari of rare sleeping landrovers drivers.
About the horn does this working normally when pressing the horn button. If not check for fuse first if still problems try connecting the horn to the battery via a tester to see if any power in the horn. Not to sure if this has a steering column ring that controls horn radio volume sometimes that fails. if so that can be fiddly as you will have a airbag and the ring but someone will come soon with a better answer shortly or better drop the same question on the discovery section.