Soak the 5 gelatine sheets in cold water for 5 minutes to soften. In a pan, bring 300ml water and the lemon juice to the boil. Add the sugar, stirring until dissolved, then remove from the heat. Squeeze the water from the gelatine and add the sheets to the syrup. Stir until dissolved, then stir in the cranberry and raspberry juice or wine. Set aside to cool to room temperature.
Divide the mixed berries (reserve a few for decorating) between 6 x 200ml plastic tumblers, then pour over the jelly to half-fill the glasses. Chill for at least 2 hours until set.
Once set, make the white chocolate layer. Heat the cream in a pan over a medium heat. As it starts to boil, reduce the heat, then stir in the white chocolate until melted, then remove from the heat.
Soak the remaining 2 gelatine sheets in cold water for 5 minutes to soften, then squeeze out the excess water. Add to the hot cream and chocolate mixture, stir, then allow to cool a little. Pour over the set jelly layer. Leave to set in the fridge for at least an hour (or overnight). Top with the remaining berries, then cover with clingfilm.