My 10yo DS2 is a chorister in a college choir. He does not board. It is a big commitment: 5 evensongs a week, meaning that he sings about 20 hours a week, routine. More if they have concerts. They only sing in university term, but tours and recordings take up a reasonable portion of the holidays. DS2 is in his second year as a full chorister, following two years as a probationer.
It is a huge commitment, for all of us, but has been great for DS2. His instrumental music has been enhanced by the choir and he has reached a good level for his age, playing in the National Children’s Orchestra and Pro Corda on the violin. Academically he is fine. An advantage of going to a choir school is that they balance up the boys’ schedules.
But, it is a punishing schedule that does not suit every child. It would have been my older DS’s worst nightmare! Your DC needs to really enjoy group activity, and needs to be well up to speed academically. The selection process is pretty reliable though, so I would go for it and see what happens!
The audition for DS was quite simple. He sang a verse from a hymn, sight sang a hymn and did a load of aural tests. He also played the violin for the school director of music (he was a beginner at the time). He did the school 7+. We didn’t prepare much as he was only 6.
Good luck! PM me if you want to know more about specific choirs.