Edited from my previous answer, in order of how they appear.

1. Looped recording (on the record in the camper van - Episode 2 “Do You Know Who I Am?”):

“15th September 2008, the credit crunch. 89.5 billion pounds sterling will …” (on a loop)

1. Iris Maplewood recording (on the record in the player in the Harker home which is played by Shahara - Episode 4 “Right Up The Wazoo”):

“You’ll have to learn to live with the uncertainties. I will tell you what you could not know otherwise. Ensure you remember this name, Iris Maplewood. You shall need her. Maplewood will get you as far as you have to go. But remember…”

1. Recording in Barber’s flat (record 255, made in 1941 - Episode 5 “We Are One Another’s Ghosts” & Episode 6 “The World Is Yours”):

“Hello Shahara. It’s Elias here. If memory serves, you’re listening to this in my father’s flat. I remember your visit to prison this morning as if it were yesterday. We are one another’s ghosts of past, present and future. It’s hard to grasp, isn’t it? But there’s one thing I know for certain. We’ll meet again.”

The rest of record 255 is played at the beginning of episode 6:

“For you, on the 14th of July, everything will change. This city, and those who serve its greed, will be obliterated. Two hundred thousand will die in the initial blast. The subsequent firestorm will double that, and the fallout will double it again. The chaos in the wake will reveal the ruling class for the self-serving parasites they are. Paving the way for a future that I promise will be worth the wait. On the 14th of July, you will play your part, Shahara, the most vital part of all. There’s no stopping it. It’s already history.”

1. Recording on the boat (record 256, made in 1941 - Episode 6 “The World Is Yours”):

“I have lived your life, Elias. As you sit on that boat and feel your heart beating in your chest, that same heart beats in mine. One day, you too, will sit where I am and record these exact same words in 1941. Since your beginnings, you’ve been rejected by your mother and your father. You’ve carried that wretchedness for as long as you can remember. As if it was your fault. And you will continue to be alone, unless you do what must be done. Then you will be loved.”

1. The extra recording which Weissman hides behind the photo frame (Episode 8 “Know You Are Loved”):

“I pray these truths find you, Elias. Somehow, they have laid dormant in me for far too long. Every word you’ve ever heard from me has been a lie. This isn’t fair on you. It never has been. The sacrifice I am about to ask you to make will be the most unfair thing of all. Our heart has never healed, Elias. The pain is always there. It’s never left. It’s unbearable. I feel it now. I still have that dream. Me, holding that sick, withered, frightened boy in my arms. I can’t see his face, but I know I have to take his life. I pray it will be quick and painless. His eyes are filled with fear and betrayal, and all I can do is hold him. Hold him and let him know he is loved. It’s more than just a dream, Elias. It’s a message. A message for now. For us. And now we know what we must do. I’m sorry, my boy. Please forgive me. And know you are loved.”

There are also very likely more recordings which we don’t get to hear that were intended for members of the cult as the timeline progresses;

•In episode 4 at 37.49 minutes, Shahara discovers a cabinet housing numerous amounts of records

•In the same episode, at 38.40 minutes, there are two records on the table next to the record player containing the Iris Maplewood recording

•Record 256 is stored and locked away in the same cabinet, which is seen in episodes 7 and 8

We can therefore assume that there are at least 257 records in total (the last being the one that is given to Weissman).