If i'm any more help than the, errrm, not-so-enthusiastic replies others have given the gauls shoul deploy like this:

-------------------Wardogs-------------------
-------------------Wardogs-------------------
---------Naked fanatics-Naked fanatics---------
-----------Druids-Swordsmen-Druids-----------
---------Druids-Chosen swordsmen-Druids---------
-----Barb cav--Forester wb-Forester wb--Barb cav-----
Barb Noble cav--Forester wb-Forester wb--Barb Noble cav
Forester wb General Forester wb
Forester wb

The wardogs charge the enemy cav, while the fanatics charge the enemy infantry. Hopefully the enemy has not got their formation together yet and they may cause some severe casualties. They will die in the end but you should move your entire formation to any land advantage and scout the land.
you could move your formation into the enemy or you could wait. Either way all you have to do is attack, draw back, attack, draw back until all your troops are spent or the enemy is dead. Keep the foresters firing and don't forget to warcry!