Thank you for the advice, Gertgregoor. Will try and get some slingers as soon as I have money..

And as an update on the current situation (on Vh-H to remind you.). I've recently destroyed the Aedui military in mainland Gaul with a few key battles and am besieging Bibracte and their northern-most city (can't think of the name..). Shame though that the Romani are coming north.. and they decline my requests for an alliance..