Help with your practice
You can find rehearsal tracks on these websites:
1) Cyberbass This uses synthesised instruments, has a speed-changer and "tutto" as well as the individual parts.
2) Learn Choral Music This uses synthesised orchestral instruments and uses the usual MIDI player on your device.
3) Chord Perfect This uses real singers, is free if you listen online, and offers options to go back by 5 seconds and slow the track down.
Recommended by Leon to help with sight reading!
English Touring Opera's Singing Lessons for Choral Singers
Free and on You Tube if you register. Click here for four singing lessons for each voice part, delivered by a professional singer from ETO.