Hi,
The MusicBrainz database is in the public domain and for the most part is populated by users/owners of the music CDs etc so its probable that some of your albums are not found because no-one has ever uploaded them.
This also means that accuracy of the information can be compromised. I have previously found typos in track names for example.
The database is searchable at the MusicBrainz website
Searching on Nicola Benedetti will produce a list of her albums currently on the database.
Search on artist with her name and then click through to get her discography (as per Musicbrainz)
If you have access to a computer for ripping, something like DbPoweramp may find the albums as it uses multiple sources.
You can then upload the ripped files to the B2
John