There's no Unofficial Community Patch like the Elder Scrolls, Vampire the Masquerade, Temple of Elemental Evil or Baldur's Gate games unfortunately.
One reason for that is because after playing the campaigns, most people move on to modules (playing/making) or Persistent Worlds.
Whereas in the games I mentioned, the major focus is the campaign or main story.
The closest thing is Kaedrin's Pack which fixes and adds: spells, feats, classes, prestige classes, races etc. It doesn't fix anything in the campaigns though.
Many modules are made compatible with it though not all and most major PWs are using it. For good reason.
I would also recommend Tony K's AI. It improves the AI of both your companions and enemies making battles much more interesting and fun but within reason. It simply makes everything smarter, not increasing their HP or damage for example.
I would highly recommend Tchos UI mods. It changes the UI to make it better for higher resolutions, so you can see much more stuff at once on your screen instead of scrolling down all the time.
I would also recommend the Appearance Changer mod. It lets change your armor pieces on the spot so you can make your character look whatever you want almost.
No more those stupid Mithral Full Plates with the weird "wing" piece.
Your characters won't look like clowns anymore with purple masks, yellow cloaks, green armor and red boots.
If you dislike the overdone spell effects, there are mods that tone them down. Like Less Obtrusive Spell Buffs, I think it's called.
You can also download head and hair packs or Xaltar's Facelift Pack (link in the post above) to make the faces more beautiful and realistic.
That's more or less what I'm always using unless something is not compatible with a module or PW. Otherwise, you're good to go.