I don't know any of the lyrics but I can give a good description;
First heard on heart radio.
Has a bleepy melody, a little like Fireflies by Owl City but sang by a woman who to me sounds a little like Dido.
Heard snips of it on radio adverts and a snip today on a c4 advert, but can never make out any lyrics to narrow it down.
I searched the charts and tried auto finder sites with no luck.