Vauxhall Astra sunshine roof leaking

Is it a factory fitted tilt/slide sunroof or just a glass panel in a metal surround unit that has been fitted later ?

Factory fitted

Some cars can have 4 drains on sun roofs , one at each corner . Front ones are usually accessible and can often be cleared with a stiff wire and then drain away behind wheel arch cover .

My Renault Clio 1.2 had a very similar problem last year, after light and heavy rainfall. Water dripped off the sun visors and onto the front seats. Thinking the sun roof was leaking, I put opaque silicone all around the rubber seal. Water was still dripping in. Applied silicone around the roof ariel base. Still the same. So I applied another wider coat of silicone around the sun roof, but water still came in. Cleaning the windscreen one day, I noticed that the plastic moulding around the windscreen was lifted just a fraction at the top driver's corner. Nothing ventured, nothing gained, I pressed some silicone in the gap between the seal and metalwork and hey presto, problem solved. I have had no trouble since.

Good you got your Renault Clio leak fixed but it is irrelevant to the members problem on her different car , Vauxhall Astra where the " water is not running away and cant find the drain holes ."