Exercise green student I believe, from my limited knowledge of the uotc, is a course for officer cadets which teaches them commando skills that are taught in the all arms commando course. These include small unit tactics, combat survival and maybe even unarmed combat ( or whatever it is called ). It is ran by 29th commando regiment regiment of the royal artillery.
Ex green student is run by the royal marines at ctcrm lympstone not the royal artillery commando unit, and from the feedback I got from a pal who attended was comprised of a lot of phys and some small unit tactics concluding with a presentation on commissioning with the RM. The lad previously mentioned said it wasn't quite what he expected and had little green training as such but was good to see how life in the RM operates from a potential future applicants point of view.
Tiktok, these things seem to differ year to year, what otc did you serve with? A few bods opted for the TA p coy last year over green student (overlapped one another) and returned with maroon lids (needless to say the oppertunity to do the jumps did not arrise) never heard of any ocdts doing the all arms commando course though?!