I had exactly the same problem as you, an intermittent Battery Warning light.
I bet you my farm it has ALTERNATOR written all over. I just changed mine this Monday.
Do not worry about anything else. Take the alternator out ( 1 hour work) take it to a auto part have it tested ( guaranteed 99% faulty) and replace it. After the electrical system work as it should again, then check the other warning or codes you may have.