I've got the waterproof version of the Lifesystems Trekker First Aid, to which I've added my epipen (rubber band to the outside), antihistamine, ibuprofen lysine, gaviscon, steristrips, a resuscitation mask, and some wound spray. I also have a small tube of hycosan night, because my artificial eye gets really dry and painful and the KY jelly recommended by my prosthetics dude stings like buggery, and some hycosan extra dry for my regular eye, which gets tired. I've got some Elastoplast Star Wars plasters, which are surprisingly good (I only wanted the BB8 tin).
I've done the full three day first aid at work course, along with first aid at sea and first aid for divers. I've maintained first aid qualifications for about 30 years now. Mostly because I'm incredibly accident prone.
Sam