Yet surprisingly lots of their tracks are on Spotify, if you can stand the odd advert
Spotify.. +Nowell+Sing+We+Clear  

If you Google the group quite a few tracks seem to be available, I've only looked at a couple.
https://www.google.co.uk/search?q=by+Nowell+Sing+We+Clear 


~~~   footer, not just because it's Christmas .... I hope we're going to concerts and buying CDs too ~~~ !