This is the final mission of the Scorchers DLC and it will come up directly after the Wellspring Tunnels (there will be an opportunity to shop and stock up on ammunition, but you won't travel back to the city).
Overall, this game is fairly straight forward with its missions and you shouldn't have any trouble with knowing where to go - the only difficult part for me was the final battle. Be sure to shoot at the armor first, and then once the armor is all gone off of the Scorcher ship, it'll have around 1/10 of its health bar left. That's when you start shooting for the blue boosters keeping the ship afloat. After that, it's a piece of cake and congratulations on finishing some DLC for a fantastic game!
Feel free to add comments as to how I can make this better!