HBO Version?

You are probably referring to the series that was done by the BBC in the 1990s. Each animated episode opened with a brief "live" vignette showing the lovely Lake Country where Ms. Potter lived, and an actress as Ms. Potter preparing to tell the story. The closing credits feature the song, "Perfect Day," performed by a singer named Miriam Stockley. All of these episodes were absolute magic and the animated portion appeared to be watercolor brought to life. These are available on Amazon. At this writing, you can find a used set for around $30 USD. Cheers.