I have started to play the new adventures that people have made for this game, but I have encountered a problem. I have an SSD drive for Windows, and have a HDD for my game files.

The default file location for new adventures is the following:

C:\Users\Public\Documents\The Witcher

Is there anyway to move this to my HDD as having such large files on my SSD is taking up a lot of space.

Symbolic Link. You will need an elevated prompt, but it should be doable.