Have also booked myself on the combined DMZ tour on the 15th December.
Had to laugh at the brief instructions, especially in the last paragraph in
RED:-
On Saturday 15th of December, COMBINED tour is confirmed for 1 adult as English tour, and your reservation number is #XXXX.
Departure time is at 08:30am from So-Gong-Dong LOTTE Hotel (near the City Hall) Main Building 6 Floor”service club” desk.
Take a subway line 2(Green line) to Euljiro 1(il)-ga station. Exit number is 8.
You should arrive at tour desk by 08:00am with your Passport on the tour day.
Tour fee is 120,000KRW per person.
You can pay on tour day by cash or credit card.
There is a cancellation charge; 50% of charge three days before the tour day, 100% of charge on two days before the tour day.
Please let me know if your schedule is changed or cancelled.
Please check Panmunjom (JSA) dress code.
1. No the color has faded or the hole jeans. (Regular jeans are OK).
2. No training wear, Military style.
3. No short pants, mini skirt and opened toed shoes, flip-flops.
4. No T-shirt without collar and sleeveless.
5. No and leather or skinny pants and leggings.
You must reconfirm your reservation one day before the tour day by email or phone (02-755-0073), either way is okay.
Because, sometimes the Panmunjom tour could be partly cancelled by unexpected military situation but we do not know when or where it happens.
And in case military or other considerations prevent entry into the Joint Security Area, it's the inevitable, so yours no refund. 
I’ll wait your reconfirmation one day before the tour day.
Thank you.
Regards,
Tourdmz.