Yup, the first Eleutheroi encounters are the toughest one for the Casse.

The "economic" approach is senseless, with only one city, no matter your infrastructure, it will be very hard and time-consuming to pay a whole good army.

My approach with the Casse: Diplomat shipped to mainland, disband fleet (not affordable at all in the beginning, as you noticed too), diplomat then makes trade alliances etc.

With the starting money, I recruit all the troops possible so I can field every possible man, while my starting armies turn west and take Ictis, which in my opinion is not so hard defended. With the recruited troops replenishing my armies, I then take on the next settlements.

The settlements on the British mainland tend to have an excellent economy, and once you have three or four settlements, the money really starts to roll in.

Conquer all of the Islands and you are unstoppable, granted. You get a sh*tload of money every turn, have a completeley safe region and can fully concentrate on your campaign in Gaul.

The most difficult part really are the first turns...