This website has some links to research http://www.schools-out.org.uk/research/contents.htm. Also, the UK charity Stonewall http://www.stonewall.org.uk/our-work/education-resources might be useful. Good luck with your work.
Some work has been done in the self-study research community (AERA SIG). You could check the journal Studying Teacher Education, and the articles written for the so-called Castle Conference of then SIG.