I'm a teacher too. Depression and anxiety are extremely common in our profession and getting worse.
Don't assume the MH team will be no help. Are you on medication? If you are and it's not helping, get it changed. Ask for s referral to a psychiatrist and to therapy, CBT or ACT if you can get the latter.
Here are some good self help books.
The Happiness Trap by Russ Harris
Feeling Good by David Burns
Hope and Help for your Nerves by Claire Weekend
DARE by Barry McDonagh
If you can get motivated to start mindfulness, that really helps but takes timewww.freemindfulness.org
Or the Headspace App which costs
This forum is really quiet at the moment because so many of us are in a bad way