Cheers fellow forumites!
Just wondering if you guys know where I could head next after doing theory grade 8. I currently write repetoir for vocals and string ensem and piano... or solo works.
Need more experience and possibly more study!
Where to head?
Does ABRSM offer anything?
(this is aside from my practical studies)

ABRSM don't have any further theory exam but other boards do.
You could take a look at LCM and TG though as they are also examining bodies they are not taught courses if that's what you are looking for.

TG and LCM both do diplomas in both general music theory and specifically in composition. TG's composition diplomas are L and F level, L has a portfolio and 5 hours of exams and F is portfolio only. LCM has composition diplomas at all 3 levels which are portfolio only.