Biddy - and anyone else who'd like it! - here we go 
Can be made egg and dairy free too, I have marked where you can sub, but I haven't tried it that way as the only egg-allergic person in my family doesn't like Christmas cake anyway.
900g total dried fruits - make it up however you like. I usually do a mixture of cranberries, apricots, cherries, sultanas, and some mixed peel, but you could use currants or raisins or whatever you like!
Grated rind of a lemon
Grated rind of an orange
Booze of your choice - brandy, rum, whatever. I use a mix of Cointreau and Apfelkorn! I don't measure - just glug it in 
Use apple juice or whatever if you don't want booze.
140g ground almonds
55g rice flour (I use brown rice flour)
30g cornflour
2 tsp mixed spice - check gluten free
1/2 tsp salt
225g butter OR dairy-free alternative
225g soft dark brown sugar
4 eggs, beaten OR sub in 225ml apple/apricots, puréed
2tbsp black treacle/golden syrup - optional
55g chopped almonds
Method:
A week before Stir-Up Sunday, I put all the fruits and zests in a bowl and soak with booze. Cover and put in fridge. Every day I get it out, stir it and add more booze if it's soaked it all up.
On Stir-Up Sunday, pre-heat oven to 150 deg C. Grease a 20cm deep cake tin and line sides and base with greaseproof. Make sure the lining comes up nice and high, over the edge of the tin.
Mix ground almonds, rice flour and cornflour with mixed spice and salt.
Beat together butter and sugar. Beat eggs in slowly. Add a spoon of the flour mix if you need to stabilise it. Then fold the rest of the flour mix in.
Stir treacle and chopped almonds into the fruit mixture, then fold CAREFULLY and slowly into the cake mix. Put in tin and level top with a spoon.
Cut two pieces of greaseproof to cover the top of the cake, with a hole in the middle. Put double layer of brown paper around the tin and tie with string. Again I make this nice and high, but be careful you won't set fire to it!
Bake for 3.5-4 hours. Take the greaseproof off the top for the last half hour if it isn't browning, although I always find I need to leave it on or it goes too dark. It's done when a skewer comes out clean.
Let cool out of tin, but leave it in its lining paper. Stab top several times and drizzle over more booze! Wrap in cling and foil and leave in a dark place until Christmas, unwrapping every so often to add more booze as required.
You can marzipan/ice it as normal.