Liturgia Horarum is the official Latin Divine Office (current schema).
If you want a version noted for Gregorian chant, I recommend:
Les Heures Grégoriennes
It’s Latin/French, entirely noted for Gregorian chant, in 3 volumes: Advent, Christmas season, Ordinary time (vol I), Lent and Easter season (Vol. II), Sanctoral (Vol III). It’s day hours only, (Lauds, Terce, Sext, None, Vespers, Compline) but everything’s there and it’s easy to use. It has Latin on one side and French on the other but you could have your English LOTH alongside to help interpretation. When using the Roman (as opposed to Monastic), it’s what I use. I do the Office of Readings recto-tono (chanted monotone).
Not cheap but worth every penny.