roof sealing

[viciousbongo]

hello
i am looking for some advice and info on sealing the roof of my vehicle. it is a bedford TL which i and my girlfriend recently bought. we are in the slow process of converting at the mo. have recently discovered to leaks from the roof. 1 at the front drivers side corner and the second from one of the orginal roofing skylights. what is the best way to seal these leaks so that they wont come back.
many thanks

[adds]

I had a few leaks when I brought my ambulance, mainly where lights and sirens had been removed, I used sikaflex sealant which I got from my local caravan dealer. Its specially made to be flexible and work with GRP and Alluminum.
I also raided the skip at the local engineering firm( with permission and found repair plates.
I think all the leaks have gone so this sealant might work for you.