Preheat your oven to 140C.
Cream the sugar and dairy free margarine into using an electric whisk until smooth. (I used a standing mixer but you can also you an electric hand mixer.)
Then add in golden syrup and mix briefly until combined once more.
Add your half a beaten egg, lemon zest and earl grey tea and mix on a medium/high speed until fully mixed in.
Next, add your gluten free flour, baking powder and xanthan gum (ideally sift it). Mix on a medium speed until the dough is well formed and a little sticky.
Bring the dough together into a flat ball and wrap in clingfilm. Place this in the fridge for around an hour. This will take the stickiness out of it and make it ready for rolling.
Before you roll out your dough allow it to get a little closer to room temperature again.
On a very lightly floured surface, roll out your dough to the thickness of a pound coin. Use your biscuit cutters to cut your shape.
Place these onto a baking sheet.
Place into the oven for 25 minutes, one tray at a time (my biscuits were very small at around 4cm square, so if you use large biscuit cutters, they may need a little longer - 30/35 minutes possibly)
Once the biscuits are done, place them on a cooling rack. Once cooled, you either eat them, or ice them.
Enjoy!