Dissolve the sugar in the tea. Chop the raisins, and add these to the tea, along with the juice of the lemon. Pour the mixture into a clean bucket and cover the bucket and leave to cool. Once it's at room temperature, add a teaspoon of yeast to the bucket. Leave the mixture for a week, stirring daily. Strain the liquid to remove the raisins, and pour into demijohns, sealing with a fermentation lock. Leave this until fermentation has stopped, then bottle it. The wine is usually ready to drink after a further 2 months.