If you're playing 3.0 and have access to the various builder books, you can set up an offense/defense cleric to just mulch things. You do need one level of paladin in the mix, or fighter. You need martial weapon proficiency more than anything. But either the free feat from fighter or the save bonus is nice too. With your stats, I'd take paladin.
A strong build at level 6 is going to be pal 1/clr 5. Set yourself up to take the church inquisitor class at level 7, which is an excellent class. Then make sure to get cleric 6. Cleric 5 is a sucky level to stop at. (Level 5 gives no BAB and no saves, it's a wasted level in a lot of ways - level 6 gives BAB and all three saves, making it an excellent level at which to stop a class progression.)
For feats, you'll want Extend Spell, to set yourself up for Persistent spell at level 9. Persistent spell is incredible for clerics in 3.0. And Extend is nice on its own for extra long stat, weapon, and armor buffs. Other than that, maybe look at item creation feats, if your campaign lets you have enough downtime to use them. Or combat feats if it doesn't, such as power attack or the various bow feats.
Given that you're short of players, and have that nice high charisma, Leadership might be a decent investment too. That'll depend largely on your campaign though.
When you say supplemental books, it's unclear whether or not you include Forgotten Realms books in there. If you have access to those, set yourself up for Divine Disciple as your 9th level, it's another nice class that adds in to the mix quite well. With this sort of build, you'll end up with insane saving throws. Your BAB won't be great, but you have buff spells to make up the slack. Also from the FR, Spell Girding is a nice pick-up, since it makes your spells harder to dispel. Essential for a buff cleric. You'll also want to invest at some point in a ring of counterspells and keep it full of either dispel magic or greater dispelling (depending on level).
So, at 6th level:
pal 1/clr 5 - feats Extend Spell, Leadership, Scribe Scroll, Spell Girding
At 9th level:
pal 1/clr 6/inq 1/div dis 1 (or pal 1/clr 6/inq 2) - added feat - craft wondrous item
From there, keep improving your inquisitor and disciple levels, unless you find some other pclass you like better. Both classes can be taken at least to level 4 for maximum benefit. By the time you get that done, you're 15th level.