Typical problems with condensation in a roof space. Caused by high levels of thermal insulation and little or no ventilation.
If left unchecked damp will build up causing possible rot to roof timbers and almost certain spoiling of ceiling décor in the rooms below.
Early improved ventilation of the attic is required: soffit vents, ventilation tiles incorporated in the roof slopes or air bricks in the gable end (or a combination of all) are possible solutions.