I’m currently listening to Dan Carlin’s “Celtic Holocaust” although I am wondering if his name is credible enough to be listed as an “academic”

To be clear, Dan Carlin is not only not an academic, but he is a terrible source of historical information. He hides behind his constant claims that he is "not a historian" while peddling a backward, sensationalised, narrow and misleading narrative of history. We had a great multi-flair team-up discussing his work a while ago, which you can read here. If you are preparing to start a history degree at university I would urge you to stop listening to Carlin immediately.

You've already got a good critique of Dan Carlin, so I'll leave that out, but I wrote a response about which ancient history podcasts I recommend (and the one to avoid most of all) for this recent post.

I will say that in my answer there, I do come down as a bit harsh on Mike Duncan's History of Rome podcast. It is very surface level compared to my other recommendations, but that's not necessarily a bad thing if you're just looking for beginner's information. As a podcaster, Mike Duncan is great and there's a reason many other podcasts cite him as an inspiration.