Preheat the oven to 165°C. Line 3 baking trays with baking paper.
Empty the contents of each cookie dough tub onto a separate baking tray. Press into an even layer, then dust with flour and roll the dough out until around 0.5cm-1cm thick, trying to keep the edges straight.
Bake each tray for 18 minutes or until golden brown. Set aside to cool.
Once the cookies have cooled, cut out your cookie house shapes. Cut 2 x rectangles (15cm x 7.5cm) for the side walls, 2 x rectangles (15cm x 10cm) for the roof and two pentagons (10cm base x 15cm height) for the front and the back walls. Flip the cookies over so the flat sides are facing up and brush with melted white chocolate (this will make the cookies stronger). Set aside to set completely.
To make the royal icing, combine the icing sugar and water and beat on medium speed for 5 minutes. Reduce the speed to low and beat for 2 minutes, then add a dash of lemon juice. Cover the bowl with a wet towel (this will ensure the icing does not dry out) and set aside until required.
Fill a piping bag with a 1cm piping nozzle with royal icing. Prepare a serving tray to build the cookie house on.
Pipe a line of icing on one long side of the two smaller rectangles and up the shorter sides. Pipe icing on the base edge of both the pentagon pieces and connect them to the smaller rectangles, making sure the rectangles sit on the outside of the pentagons.
Fill the inside of the house with 500g or more of the assorted lollies.
Pipe royal icing on the outside edges of the two roof cookie pieces, and place on top of the cookie house.
Once assembled, decorate your house as you wish with remaining icing and lollies.
Make sure to bake the cookies through, otherwise they will be too soft and the house will crumble.
If your royal icing is too runny, it won't set. If the icing looks too runny, add more icing sugar.