Finished, but can't parse 3d even after reading Brendan's post 13. First word of clue is definition, first letter of answer "first class", but beyond that ... ?
Foi: 2d
Loi: 24d (all PhD students have one, and some grade borderline cases at UG level, at my redbrick unis)
Cod: 26 was fun, and some anagrams such as 14, 12 were very clever