You can find a good list and discussion of English translations of a number of Hildegard's works here. The following is a selection from a letter (translated by Abigail Ann Young) in which she explains her own view of her visions:
O faithful servant, I, poor as I am in womanly form, am speaking these words to you again in true vision. If it pleased God to console my body as He does my soul in this vision, the fear would still not recede from my mind and heart, because I know that I am still a mere mortal, although from my infancy I have been in enclosure. Moreover many wise men have been so infused with wondrous deeds that they opened many hidden things but, as a result of vainglory, they attributed those deeds to themselves and so they fell. But those who draw off wisdom from God in the lifting up of their soul and account themselves as nothing become the columns of heaven, just as happened in Paul's case. He preceded the rest of the disciples in preaching and nevertheless regarded himself as of no value. John the Evangelist also was full of gentle humility and therefore he drew forth many things from divinity.