Chandos is amazing...they have introduced me to a whole world of music I had never heard of...so many composers who fell into obscurity for little or no reason (save that their music went out of style after a time). I started listening to a few composers, and over time have come to appreciate so many others...it's really amazing, the amount of music that is out there...make the jump...you won't be sorry!
I think the 30 cd Chandos box-set would be a very specialized item for me, but the individual Chandos releases of British film music and their composers---and there must be nearly 20 of them by now---are an indispensable record of the history of British film scores from the 1930s onward.
I try to buy a few each year, and I've got a nice collection of them now which I love.
This has been a very worthwhile and necessary ongoing music project and Chandos should be congratulated and supported for doing it.