Cheers mate. It's all good.
I expected to be able to direct it to a specific drive or something, but I just had choices between the types of scans (I did select to search for root kits in the settings).
It's currently taking it's time searching for updates again for some reason as a first step.
I am not sure; there may be some minor limitations using it in this manner. (I haven't done it myself )
Note to self: read the descriptions
I suspect something may be awry with this, the check for updates step has been running for 13 minutes...
Edit: restarting it a few times got it going for some reason.