I know the ABRSM has put PDFs on its website so that students can see the sort of questions they'll face in the online theory exams. However, PDFs don't provide the authentic online (or at-the-computer) experience. Do colleagues know any materials that do?
I do know of one possibility. See
Does anyone know of anything else? (Won't the ABRSM post the grade 5 exam of August 26 as a 'past paper'?)