The first place to start is the BSS Support charity, below. They have lots of links and their Secretary can answer any questions you may have.
www.bss-support.org.uk LOTS of BS information and support here. You can listen to Joy Schaverien’s 33 minute talk on “Lockdown and the Resonance of Past Captivity” from the Nov 2021 Conference as well as more recent videos and recordings from the Conference in November 2023.
www.boardingschoolsurvivors.co.uk Workshops for BS survivors AND training for therapists. Nick Duffell’s books. And more.
Boarding Recovery is a growing network of therapists who have undertaken specialist training to work with boarding issues.
And there is help too for family and friends see here: https://www.boardingschoolsurvivors.co.uk/help-for-family-and-friends/
www.joyschaverien.com Author: Boarding School Syndrome, Broken Attachments, a Hidden Trauma.
Boarding School Action can be found on a Public Facebook page here. https://www.facebook.com/groups/500138323432525
There is also a Private Facebook page for Boarding School Survivors (not affiliated with Nick’s work above). I find some of the stories shared incredibly illuminating and helpful.