Preheat the oven to 180ºC/350ºF/gas 4. Combine the margarine, cinnamon, ginger and orange zest in a bowl. Use a small amount to grease a medium ovenproof dish (roughly 20cm x 25cm), then spread the remaining margarine onto the bread.
Halve the bread slices diagonally, then place roughly a third into the dish in a single layer. Roughly chop the apricots, then scatter a third into the dish along with a third of the sultanas. Cover with another layer of bread, scatter with more dried fruit, then cover with the remaining bread. Set aside, reserving the remaining dried fruit for later.
To make the custard, halve the vanilla pod lengthways and scrape out the seeds. Add the seeds to a medium pan with the remaining custard ingredients and 400ml of water. Whisk well until smooth and combined, then place over a medium–low heat. Simmer gently for 6 to 8 minutes, or until the custard is almost boiling and coats the back of a wooden spoon, whisking continuously.
Pour the custard over the bread then scatter the remaining dried fruit on top. Leave to soak for around 20 minutes, then place in the hot oven for 25 to 35 minutes, or until lightly golden and starting to set.
Meanwhile, gently warm the marmalade in a pan over a low heat. Once the pudding is ready, brush over the warm marmalade, then return to the oven for a further 5 minutes, or until golden and sticky. Allow to cool slightly, then tuck in.