As well as training for staff, there are also some nice modules to use with students, though they are secondary school level.
Go to https://lessonbee.com/ – I used the mental health and wellbeing units with students with autism and anxiety/depression and they were useuful. Though I had to pay for the unit ($12) I would have been able to re-use it I am sure.
There are free lessons on there as well if you don’t mind searching. It is USA based though, so do bear that in mind.
Thrively is another good site, but again secondary-level. It helps with units on goal-setting, resilience, gratitude and so on.