The Julii are probably the most difficult of the three Roman factions. Expanding north into Gallic territory (meant to emulate Julius Caesar, I suppose) means slogging through pi$$-poor barbarian country. Take the two nearest Gallic cities (Mediolanium, and Patavium) then head to Greece where the richest provinces are

If the Senate wants you to cross over the Alps....tell them to take a hike....