Place both the granulated and brown sugar, margarine, golden syrup and milk into a saucepan and heat gently, stirring mixture constantly, until it is smooth. Pour into a large bowl.
Sieve the flour, baking soda, cinnamon, and ginger together. Stir into the wet mixture.
Line a 10” square tin with baking parchment and pour in the dough. Cover it with cling film or baking parchment and leave for eight hours in a cool place. Don’t place the dough in the fridge.
Cut out templates for the ginger bread house on paper first, then trace and copy on cardboard. You will need two templates for the front of the house, one for the side and one for the roof. Once baked and completely cold, place either in an airtight container or wrap in cling film. You will need to roll out and bake two sides for the house, two for the roof and two for the front and back of the house.
Cut out two windows on each side of the house and one window at the front of the house.
Divide the dough into six equal portions. Use a little flour and roll out one portion of the dough to about 1/2” thickness. Make sure that before rolling, you cut out the baking paper to fit a baking tray and that one of the templates for the ginger bread house fits on it. Put one of the cardboard templates on top of the rolled out dough and cut around the shape. Place the baking paper with the gingerbread on a baking tray. Refrigerate for 1 hour until the ginger bread is firm. Roll all of the gingerbread scraps left over together and wrap in cling film. Keep the excess gingerbread dough for making extra decorations for the gingerbread house.
Bake the gingerbread at 180oC / gas mark 4 for 25 to 30 minutes until it is dark brown and firm to the touch. Make sure that the large pieces are baked all the way through. You will need to cook the gingerbread house in stages.
When the gingerbread is nearly cooked, remove from the oven, place the template on the cooked gingerbread and carefully cut around it to trim to the exact size and shape.Once it hardens it is more likely to break if cut then. Return the gingerbread to the oven for five more minutes.
To assemble the gingerbread house
Draw a rough outline of the house on a very large tray, cake board or piece of wood. This will show exactly where the house will be attached.
Next, make the icing until it is stiff. Cover with cling film or a damp clean cloth to prevent it from drying out.
Fill a piping bag with icing or use a pallet knife to spread a generous amount along the edges of the house. Spread royal icing where the house will stand and pipe it along the edge of each piece of the house. Stick one side of the house down onto the icing. Attach the front of the house to the side and then the other side to the back. Pipe some more royal icing along the inside and outside of the gingerbread house where all the edges meet to ensure that they are well stuck together. Inside the house where the windows are, use a little icing to stick the gelatine sheets to give the effect of a glass window.
Pipe along the edges of the gingerbread house where the roof will attach and stick it on. Carefully place one side of the roof followed by the second.
Colour one packet of roll out icing with red food colouring. Roll out half of the red and half of the white icing. Spread a thin layer on to both roof pieces and place a row of the red tiles followed by a row of white along both sides of the roof.
Roll the remaining red and white icing into two long sausage shapes and twist them together. Pipe more around the edges of the house and stick the red and white twists to it.
Use any leftover gingerbread dough to make a door, Christmas trees, fence and snowmen to decorate the house.