From my trip last year:
A. wearing helmets with reflective stickers fitted.
I wore a helmet but no stickers
B. Carrying breathalysers
Didn't bother as there's no penalty for not having them
C. Reflective triangle to be carried within the group
Each vehicle needs to carry one.
D. Reflective Tabbard to be carried
One per seat and accessible from within the vehicle.
E. Carrying your licence, insurance and MOT
Yes, licence, original reg document and original insurance document. I'm not sure you need your MOT but it can't hurt to bring it along
