How to defeat hostile Goblin Camp?

Its my first time playing Baldurs Gate, while I love it and also have been playing DnD for a while, I am not a massive strategic gamer and just game every now and then very casually.

I already rescuded Halsin and defeated the leaders but then teleported to a way point because I could not possibly defeat the goblins outside of the building.

I came back to the goblin camp for two reasons: I wanna rescue the owlvear and I want to get some xp before fighting "ethel" (currently level 4).

The camp is now instantly hostile when I show up without any chances to get in other by fight. I mean it makes sense, I killed their leaders. But I still cannot defeat all those goblins. I have one invisiblity potion to sneak someone inside but the rest is just horribly placed right in front of the gate all together.

Have you any tips for me, things I just havent triee or figured out yet?