Thank you to those who have alerted me to a new publication available through the Le Barroux online shop, an edition of the Nocturnale Monasticum, providing the Latin texts for Matins.
This a fantastic step forward given that copies of the 1962 (and indeed earlier) monastic breviaries are very hard to come by, and extremely expensive!
I will try and say more once my copy of the book arrives, but for now, the book is the result of a joint project between the monasteries of Le Barroux and Le Garde, and is available in both Latin only and Latin-French versions.
Alas, the book does not seem to contain the chants for Matins, but we can pray (and beg!) for that to be the next stage.
And of course hope that a Latin-English version might be made publicly available soon as well...