Okay, I may NOT be able to make a 100% nature - Oriented pary, but I can try...

Aasimar Morninglord of Lathander(Or battleguard of Tempus/silverstar of Selune)
A Human/Half - Orc Barbarian
An elven(any) Ranger
A tiefling thief
A Half-Orc Druid (Or Half-elf)
A sorcerer.

Any other suggestions? This is my idea opf a "Nature" party.

Yes

Ranger

Barbarian

Druid

Druid/Ranger

Ranger/Barbarian

Well this is not really a list of a party just some nice combos.

Role - playin' it now. A fun, really. The only problem seems to be that the only one that can wear heavy armour is my cleric...

Is the lack of ability to wear heavy armour a significant weakness?

Well, you can multiclass the barbarian with a fighter and that will allow him to wear heavy armor.

You could do the same with the Ranger, but that's iffier. If you're playing a high DEX ranger, you may be better off not trying to go for the heavy armor. Also, if your ranger wears anything heavier than light armor, the virtual dual wielding goes away.

All in all, the only characters that "need" to wear heavy armor are your tanks. Hi DEX characters can make out just fine with really good light armor and have just as good an AC as a low DEX, heavy armor wearing tank.