Garage roof leaking

[mrdman]

Hi,
I have a garage that is leaking and dripping down the seams between the long sides of the corrugated panels.  Angle I'd estimate at 10 degrees pitch.
When it's raining heavy, I notice a small drop every second or two.  I presume it's like that everywhere.  (I've only removed one "ceiling tile" which is just a Rockwool batt!)  
So my question on this front is, what would be a good solution to fill the seams?  I was thinking maybe caulking it with an elastic polyurethane.

The sheets are connected via a threaded J hook strapped around the rafters (there are no battens) which protrudes a couple of inches through the top of the roof and is fixed with a nut.
 

The biggest leak and real problem is a stream coming down the front internal wall, which I believe is due to that screw which is half up in the air which you can see in the picture.  It's roughly in that area anyway.    
So my question here is, what would be a good solution to seal around the protruding nuts and bolts.  And what to do about the other screws. I've not been up there yet, as trying to get as much info on the ground first, but I guess the question is if they are fixed into anything underneath or not.

Any help and advice greatly appreciated!  



PS. My eventual plan with the garage is to have it as a nice workshop.  I don't have any lights up yet due to the water ingress.  But my plan is to fix the leak (maybe a bead of polyurethane on the seams and replace the screw and rubber washers where needed), then put up some XPS 30mm as "ceiling tiles" rather than the rockwool batts. Then add some ventilation between the roof and insulation.   Then some lighting, and it'll be a usable space.

[TonyT]

Use some clearCT1 silicone it works on damp materials and will seal problem area,

slacken off j mounts some CT1 on the roof side and tighten down, CT1 squishing out under washer 

[ToughButterCup]

1 hour ago, mrdman said:

...

  But my plan is to fix the leak... then put up some XPS 30mm as "ceiling tiles" rather than the rockwool batts. Then add some ventilation between the roof and insulation. 

...

 

Good plan. From the images, I'd suggest that there's plenty of ventilation as it is.