Wow! I’d love to get my hands on some of those instruments. The intricacies of all the voices and instruments is amazing. What’s also amazing is finding something like this on the British record charts. I’d like to know what they are singing. I don’t speak Latin very well.
The title of the Mass is in Italian, meaning "Behold so blessed a day" and the music is based on the melody of the motet "Ecce beatam lucem" or "Behold the blessed light".
SanctaMissa.org has the side by side Latin and English
Index
http://sanctamissa.org/en/tutorial/ordo-missae-0.html
Prayers at the Foot of the Altar
http://sanctamissa.org/en/tutorial/ordo-missae-1.html
From the Introit to the Offertory - includes Kyrie, Gloria, Credo
http://sanctamissa.org/en/tutorial/ordo-missae-2.html
From the Offertory to the Sanctus - includes Sanctus
http://sanctamissa.org/en/tutorial/ordo-missae-3.html
Canon of the Mass
http://sanctamissa.org/en/tutorial/ordo-missae-4.html
From the Pater Noster to Communion - includes Pater Noster and Agnes Dei
http://sanctamissa.org/en/tutorial/ordo-missae-5.html
From the Ablutions to the Last Gospel
http://sanctamissa.org/en/tutorial/ordo-missae-6.html
Leonine Prayers after Low Mass - includes Ave Maria
http://sanctamissa.org/en/tutorial/ordo-missae-7.html