Has anyone any knowledge about internal moulded panel doors ............
snip

If all you want is a visual divider between rooms, then the cheap B&Q jobs
are lightweight (therefore easier to fit) and you will probably find a style
to your liking. Make sure you fit the lock and hinges on the correct door
edge. There is a block of wood for the latch mechanism in one side only.

If you want any sort of noise barrier look for something more substantial.

Phil