Hi again,
I basically deleted all the files pertaining to RStudio in the Library folder, did a new install, and although initially it was blocked, after ten seconds it restarted working. Hopefully it remains that way.
Thank you @andresrcs for taking the time, I imagine it is a fairly standard behaviour on your part but to newbs like me who do not know any better it makes a huge difference to have someone help out.
All the best!