Preheat the oven to 180C/160C Fan/Gas 4 and put a small plate in the freezer. Grease and line the base of a 20cm/8in springform cake tin.
For the fruit, combine the dried fruit and lemon juice in a bowl. Coat the fruit in the flour and stir in the lemon and orange zests.
For the cake batter, cream the butter and sugar together until light and fluffy. Gradually beat in the eggs, beating well between each addition. Stir in the remaining ingredients and the dried fruit mixture.
Spoon the mixture into the prepared cake tin and bake for 1 hour, or until a skewer inserted into the middle comes out clean.
Set aside to cool, then remove from the tin, remove the baking parchment on the base and place on a wire rack to cool completely.
For the toffee sauce, combine all the ingredients in a large saucepan and cook on a low heat for 30 minutes, stirring often, until smooth and bubbling (if using a sugar thermometer it will be 115-120C). To test if it is ready, remove the plate from the freezer and put a teaspoonful of the sauce in the middle. Leave it for a minute then test the consistency - it should be spreadable and not runny. Transfer to a bowl and leave to cool and thicken to a spreadable consistency.
Once the cake is cool, slice it in half horizontally. Place the bottom half on a serving plate and spread the toffee sauce on top. Sandwich with the top half and spread more toffee sauce neatly all over the sides and top of the cakes.
To make the decorations, if using, make a batch of caramel by dissolving the sugar with the glucose in a large saucepan. Cook the caramel until it is a deep amber (about 185C on a sugar thermometer) then set aside to cool. Line a baking tray with non-stick baking paper.
Once the caramel has cooled and thickened, drip caramel over the sides of the cake so that it streaks down to form irregular shards. The caramel will nearly be at the point where it sets solid, so you need to work quickly. If it hardens up completely then warm the pan gently to loosen it again.
Spoon some of the caramel onto the prepared tray to form irregular shards that will decorate the tops of the cakes. Set aside to harden.
Finally create spun sugar to dress the cake. Gently warm any remaining caramel and then take 2 wooden spoons and coat the handles with a small amount of oil. Secure these to the worktop with a heavy tray so that the handles are poking out. Cover the floor with paper because you’re going to be making a mess! Once the caramel is the consistency of runny honey, dip a fork into the caramel and flick it between the oiled handles. Collect up the spun sugar and arrange on top of the cake. Dot edible flowers all over the cake to finish.