Hi

It sounds like condensation probs are your woe.

The easiest idea to install more ventilation right up in the eaves to encourage some airflow to flow along the underside of the sheets and try and stop the moisture building up.

Cheap alterntive could be to hang some visqueen up (make sure its baggy and not tight underneath the roof, say 200-300mm away and loads of gaps front and back for air ventilation) and use it as a channel to shed to water off towards the back/front/side of the garage.

That said, this is all trying to rectify a problem with a garage you rent that the council have just re-roofed....sounds like the sheets installed (whilst waterproof) are not functioning correctly. Some of the NT boards can actually absorb the early morning condensation and slowly evaporate throughout the day. Get the council to sort it.

Silver