It has 4 connections MAIN (Live and Neutral) and LOAD (Live and
Neutral. Am I correct in assuming that I need to run one cable from
the CU to the new meter (connected to the MAIN terminal) and then run
my ring circuit from the LOAD terminal? As the new meter has no earth
connections, I also assume that the 3 earth wires will simply be
connected together?

Yes on all counts. Meters are usually run in double insulated singles.
Technically, you shouldn't use T&E (or single insulated singles), as the
outer sheath will be cut back and accessible. I'd suggest running the T&E
feed and load cables to a junction box (a simple double socket and blank
faceplate would be good) and running the correct cable up to the meter on
short double insulated tails from there, with the earths connected inside
the box.

Christian.