DO EVERYTHING YOU DO TO KEEP YOURSELF DRY AND COMFORTABLE. I would put on "dry everything", drain the bladder and apply a clamp. (You are only traveling for an hour.) Take a plastic container with you (aspirin bottle, etc)in your pocket. You may need to wear a jacket with a pocket on each side. In one pocket, put a dry washcloth and insert a clean, dry, washcloth into your container. The other pocket is for stashing the clamp (later).
Upon arriving, go to the restroom, sit down, pull down your pants and undies and push them toward your knees (so they don't get wet), and remove the clamp. Put the plastic container in place...stand up and pee into the container. EMPTY THE CONTAINER.
Pull up whatever you are wearing to keep you dry. Wipe the inside of the container with toilet paper or with your clean washcloth. Put the container back into your pocket. An alternative would be to put your accessories in a plastic Walmart bag and carry it with you...everywhere 'till you get back to your car.
(The clamp and the plastic container are your best buddies.) I would do this to serve my own interests in keeping dry and being comfortable...nothing to do with the doctor. Go over this list and see yourself doing each thing. See if it all clicks in your mind. I did that as I wrote this and I think it puts everything in place at the right time.
I have not mentioned what to do with the bag while you are working out of it. Is the floor clean? May need another bag to put everything in. Or maybe a jacket with pockets would be better? This plan would give you dry pads to leak into after you process in the restroom.
After visiting the doctor, return to the restroom and put the clamp back on. You should have enough pad capacity to make it back home. The restored clamp will help you return home, mostly dry.
