Got it Toby - Will keep this in mind going forward.
Thank you, Ken. Your solution was very helpful, just what I was looking for. It was clear that I had to first edit my Excel spreadsheet (I removed the https:/ prefix for my URL field) to suit what Tableau Public was looking for.
I found that https:/ <ATTR(URL)> in URL action is a powerful and simple solution for dealing with situations where each row has a unique URL associated with it.
Great. Glad it's working for you!