Stopped my roof leaking by just running window mastic from Focus along all the seams. Bunge up other holes in bodywork and round edges of floor panels with it aswell.
got annoyed with a clever leak that dribbled onto my seatbelt...
used rtf in the end... all dry!
might splash out and get some silicone from 'ardware shop to seal the roof leak and the draught coming from the deepest recessess of the instrment panel...