There is just so much to see it's difficult to know where to start but try......in a North to South order the main sites for the Somme Battle are
The cemeteries clustered around the village of Serres ( site of the demise of the Bradford Pals Battalions)
The "sunken lane" and the mine crater to the west of Beaumont Hammel
The Canadian Memorial & preserved battlefield between Auchonvilliers and Hamel
The Thiepval Monument to the "missing"
The museuum in Albert
The huge exploded mine crater just to the south of La Boisselle
High Wood Cemetery (the "Bois de Fopurcaux" on the D107)
The South African Memorial just to the East of Longueval, in the Bois Delville
If you want to see the point of furthest British advance, go to a monument 1km North East of Guedecourt on the D74e ( for reference the front line on 1st July roughly ran Gommecourt-Beaumont Hamel-Hamel-Thiepval-La Boisselle-Fricourt
For the Candaian battlefied travel north out of Arras on the N17 to the Canadaian Memorial at Vimy Ridge. Here there is a preserved battlefield and you can still walk through the underground tunnes theyconstructed to surprise the Bavarian forces and sweep them off the ridge. Of all the sites, this is the most impressive ( although of course all have their own sadness and poignancy).
You should note that just south of Arras around the village of Wailly, 1n the 2nd World War the RTR gave Rommel's 25th Panzer Regiment a bloody nose on his advance to Dunkirk and caused him to check his whole advance ( believing that the Brits were being attached by 5 UK Divisions). Not much to see there now unfortunately .
Ian
Istanbul