about the celts

i just got the play the world add-on pack. mainly for the new civs, in particular the celts.

i had a look in the book to see what it said about them and about government it says:
"Prefered Government: Despotism
Shunned Governemt: Republic"

considering republic is my favourite form of government and despotism my least, i wasn't happy. i still want to play as the celts though ('cos i'm patriotic like that). but in what way does this affect gameplay? are they more/less productive under despotism/republic? does this have a major impact? and is there a way i can change it.

btw: i usually play roman republic.

As far as I know, that setting only matters when the AI plays the civ. The attributes for each type of government will work the same for you no matter what that says. Good luck!

The preferred/shunned government setting is something used to calculate the AI stance toward other civs. They're more polite to a civ in a preferred government. In this case, the celts are nicer to you if you're in despotism.