For the actual roof itself (presuming you have an original - Made of vinyl)
Now available in Litre bottles - Autoglym Plastic conditioner. It helps the water bead off rather than soaking in and causing leaks.
http://www.amazon.co.uk/gp/product/B...VBGTFBTWBFDCVV
Check condition of the rubbers. if they are excessivly squashed then adding some foam strips into the void inside them will bulk them out to create a better seal.
Also water can build up behind the front corner, so check for any evidence of cracking in the vinyl near the front and along the seam that runs backwards.
Steve M
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Its all gone Norfolk!!!
Now in the Lotus position.