- Overall map of your route
- Directions to the cemeteries
- Maps of the cemeteries themselves
Villers-Bretonneux is more simple as the battalions are all Australian and listed in numerical order, starting with the infantry then the more specialised units such as the Pioneers.
I'd also recommend reading up on both war records and battalion histories to track where your ancestors fought. You want to pack light, so I recommend recording the information in a table you can print out or something similar.
*I caught up on David Combe's newest, "The Three Rabbits Alibi". David takes stories discovered from some seriously top level Troving and then investigates them. Archives, Trove, colonial history and true crime in one delightful package.