Hi Stuart,
Welcome to the forum first of all !
Now - it would be handy to have some pictures posted up of your car so when you get a chance
Assuming your car is standard then you have a late Beta Coupe which is fuel injected, the date of registration backs this up as its an 1983.
The VX or Volumex refers to the cars that have superchargers fitted. (Pretty much all you'll see/hear about are VX Coupé & HPE's although there was a Trevi VX)
The HPE refers to the High Performance Estate model, these run same engines as the Coupé, Spider and Belina bodied cars but obviously the bodyshell differs.
Spiders are the convertibles and the Berlina is the Sedan version, then theres a few other shaped cars like the Monte Carlo which has pretty much the same engine but it is a Rear/Rear configuration (engine in the back and RWD) There is also the Trevi which is part of teh Beta family but with more square/boxy shaped body.
Have a wander through the members gallery and you'll see all of teh different models - even thecolonels big old Gamma! Which was the next model up from the Beta