You have to keep the same mountings when installing and playing. Your mount c suggests you don't do this.
Follow the 60 seconds guide in my signature and you should be fine.

Ahh cheers for that. I had read the guide but neglected to realise it prohibits changing directory as well.
I just re-installed it using the c:\rallyc mount and installing to plain old root c: and all is working now.

Legend.

😀 have fun playing

Another quick one for you.
The game runs but with no music. Sound is fine but I can't get music on the menu or in game.
I've downloaded VDMSound and installed it, set DOSBox to run using VDMS and it still doesn't work.
I've also tried using the dosdrv command to run it manually but it seems to hang on loading VDDLoader.dll

Have I just missed one little thing again?

You can't use dosbox and vdmsound together.
maybe use a different mount line to enable cd audio support (-ioctl)

if all else fails you may need to rip an image (bin/cue, but under no circumstances iso, since that loses audio tracks) and imgmount that instead.

I'm pretty bad at the command lines here.

I tried changing my mount parameter for my CD Drive to
mount d: d:\ -ioctl cdrom
and then game stopped loading due to the mount parameters changing since install.
I then tried re-installing using that same command and it fails to install any files after I input the directory to install to.

Obviously that's not what you meant for me to do.

The cdaudio appears to be bonus material that is not used in-game, at least on some versions. After installation the game is configured to use the speaker, and you have to configure it for SoundBlaster. It depends on which version you have, but this thread may be helpful:
Network Q RAC Rally

After reading through that I'm inclined to believe my copy is one of the re-releases that was mentioned as my sound works perfectly fine but no music. I don't have any playable audio files on the CD either, they're all data files so my guess is I'd have to find a menu.exe file that actually uses the copy protection because mine doesn't, and that's a thought I don't exactly relish seeing as I don't have a manual with my game to pass the copy protection request. At least the game is playable, I'm more than happy with that.

Cheers for all the help, guys.

You can't easily tell whether you have a mixed mode CD (data and aufio) in Windows. Windows will only show the data.
As for the command line, read the readme on how to pass the coreect parameters