Here's the answer from the blood donor service themselves. Like you, I was looking to buy the track. But it's not good news.
Thank you for your inquiry regarding the music used on the Give Blood TV advertisements. This music was specially composed for the National Blood Service for this project. As it is specially composed, there is no CD that is available with this music on. The total piece length is only about 40 seconds and as such we have no plans to record this music for more general availability