All as advertised; it all fitted and worked out well.
The Trim Tab hinge was secured by with a bespoke metal clamp which was held up against the spar with a #6 screw installed into a Click Bond CB6D1YCR06-1P nutplate behind the spar.
The mating up of the Elevator Horn turned out to be a non event; it seemed at first that the horns were the wrong way round and impossible for them to rotate in unison.