Actually you can do that with a straight class cleric. The best part about doing that is your cleric spells go up a LOT faster this way - and there are some cool ones out there.
I love clerics (that is my thing) - fighter, mage, cleric (tons of spells, leveling up is slow in the classes, tho), cleric (spells go up quick, especially you turn undead which becomes AMAZING) and fighter cleric (you don't get any real advantages here that I noticed).
It is up to you and your playing style. Clerics wear armor. Mages can't. Wearing armor and weilding a flail or mace can do rightous damage... but the Crom Faeyr is amazing in the hands of anyone. I tend to go for the Flail of Ages or the Mace of Disruption (for undead).
I don't think you really know how you play until you go through a couple of chapters in the game with a character and party.. figure out what character traits you use the most or the best way and take advantage of that playing style.
Enjoy!
