If you're already first aid trained then a brush up reading the book and watching online videos with a willing....or non-willing subject to practice on would be enough I'd reckon. Tailor your learning to situations you'll likely encounter on the trip.
Have planned in your head...what will I do if this or that happens. How can I adapt my training for the outdoors.
Prepared is forewarned in my view. It won't happen...enjoy the trip, right.