"One Day Like This" by Elbow
It is a song called 'Deep Blue Sea' by Grizzly Bear, and the version you are looking for is the Daniel Rossen Home Recording. It is on iTunes.
It's "Get That Feeling" by Curtis Knight & The Squires, featuring Jimi Hendrix on guitar.
Friendly fires - Jump in the pool
It's called I Giorni by Ludovico Einaudi http://www.youtube.com/watch?v=jhuGfmoIv_M (the piece used for the ad starts around 1min 11secs into the video)
the music used in bbc xmas film trailer is L.O.V.E. by V V Brown
The Wombats - Let's dance to Joy Division? http://www.youtube.com/watch?v=ayuooyWPEUc
Found it, it's 'I gotta feeling' by the Black Eyed Peas
Beautiful Morning, by The Rascals
It's Crystalised by XX.
It is from The Battle of Evermore, by Led Zeppelin, from their untitled fourth album, which is usually referred to as Led Zep IV. Gareth
Stina Nordenstam - Crime from the Album 'And She Closed Her Eyes'
Is it Fever Ray? It is very lovely.
Ellie Goulding - Lights
took me ages to find it but its (Foals - Spanish Sahara) :)
Erik Satie - Gnossienne No.1