If you are still stuck, don't have a save before then that you can reload, and don't have access to the homestead yet, you may be able to destroy a door if you have the Fireball spell (Flare probably won't do any damage if you are at level 2). The Phoenix Dive skill would let you get out, if you had it or recruited the companion who knows it. The mage's Teleport skill will work, as well.
Have your mage stand beside the hatch, as close as possible, against the wall (move the baskets there out of the way), and your archer also by the wall. Rotate the camera as far as you can to see the outside wall, then Teleport your archer outside (click on the bottom window sill, in the middle or slightly to the right, where the 'hatch' tooltip is up but there is no 'blocked' message. If your archer ends up inside, put a couple crates beside the chair with the sheet over it, and maybe one of the screens beside them, to block off the inside destinations.
Once your archer is outside (with the characters still liked together), head to the town hall next door and take the stairs up to the library to get your mage out (or the King Crab inn, etc).
