It's not the getting inside that is the problem. That is easy-peasy.
It's the getting inside, convincing everyone to drop everything and get the f--k out right now, and then getting out of the fence before the patrol comes around the corner and find a bunch of sleeping allies. I can't imagine it takes more than 5 minutes to circle the church with 12-14 kobolds and lizards. And it will probably take more than 5 minutes for the civilians to get the stuff together and out the door. And the last thing I want is to try to run for the rat infested bolt hole of the castle with 20+ civilians while 75 enemies bear down on us. The civilians will not be moving at 12" as some of them will be old, injured, or children. The brigands won't have anything slowing them down, and they'll have ranged weapons.
Frankly, if everyone says, "we can't possibly do this without killing most of the civilian" Tina will agree and suggest we retreat before attempting this.