The Imperial War Museum holds the BBC Monitoring Service reports - transcripts of German-language broadcasts during the War. How comprehensive they are, I'm not sure - or whether they held on to the original German for that matter. Sometimes British agencies kept the original text as well as translations, but quite often they didn't.
This is an interesting line of inquiry. The "Flensberg Group" continued to operate through 28 May. The Lage Ost maps depict both Armee and Korps HQs still in the field in northwest Germany through 21 May.
I just called a friend of mine who is working as a journalist there: There are no audio-medias available from that time. Print media are stored on micro-film. You can call: 0049-461-8080 and demand to be conected to the "poststelle" they can reprint daily newspapers for every single day, but it will take about three weeks and cost round about 2 Euro per page.