I think I narrowed it down to some kind of incomplete MySQL change in my local development environment, so a rather freak occurance.
This Stack Overflow thread got me out the stuck position: https://stackoverflow.com/questions/15694168/error-tablespace-for-table-xxx-exists-please-discard-the-tablespace-before-imp
I had to delete a few 'session' table files from the MySQL directory, only2 out of 3 of the required files per table were there. So it was casuing some kind of stuck state were it couldn't setup or drop the sessions table.
All good now, thanks for your help!