Kit and Teen Breathe magazines have some free downloadable mindfulness packs. You can find them at https://lovattsmagazines.com.au.
Big Life Journal has some free printable including things to do at home for teens. You can find it at https://biglifejournal.com.
Access to The Brave Program an online course by Queensland University is free. They have pre-teen and teen programs. You can find them at https://brave4you.psy.uq.edu.au.
Smiling Mind has free web and app based mindfulness and meditation app. You can find them at https://www.smilingmind.com.au.