Jennie

this may be too late, but i think, considering the beauty of the birdsong in question, that its never too late...

1. go to FreeSound.org and type 'nightingale' into their search line
they have many examples, a few of which run to a half hour

2. NickPenny.com      has a CD of birdsong, including a superb nightingale track; teh same track can be heard on YouTube

3. The Birders Market & Birding-radio.co.uk      has an entire CD devoted to nightingale song

CF Bull, USA