If you can think consciously about singing from your diaphragm, not your throat, that might help. I'm sure you've heard that before----any chorister has. Supposedly vocal exercises before the actual music help also--gradually exploring and extending your range. And then there's that question of chest voice versus head voice (for women)--somewhat analogous to full voice versus falsetto for guys. There are quite a few Mudcat experts on that--maybe some will comment.

As for recovering from the sore throat you now have, all I can think of is the old "lots of liquids and plenty of rest".

Good luck to you. Group singing can be a wonderful experience (as you no doubt know).