[?] How to repair a garage roof that is letting in the rain.

My son's 50 year old house has a detached garage with a roof made of sheets of overlapping corrugated mineral material (asbestos-like), sloping up from either side of the garage, and capped along its top by overlapping /\ shaped pieces of the same material. The roof is well supported inside the garage by means of a criss-cross structure made up of angle steel.
When it rains the garage roof leaks in some places - not a lot, but enough to wet anything stored in the wrong place below. When I went inside the garage and looked up I could see the sky through quite a few gaps where the /\-shaped capping pieces were supposed to be covering the two sloping side-pieces. The outside of the roof is covered by quite a lot of moss, much of it around the capping pieces so I'm wondering if its growth may be responsible for some of the problem.
I would like to ask three questions :
1. What is the most cost-effective way and best material to seal the gaps in order to deal with the water-ingress problem?
2. Are the roof sheets really likely to be a dangerous type of asbestos and, if so, what additional care should be taken handling/repairing it?
3. What is the best, and safest, way of actually getting onto the roof in order to clear the moss and actually effect the repairs?
Many TIA - Dave.
--
David C.Chapman - ( snipped-for-privacy@minda.co.uk)
--------------------------------------------------------------------------
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

you asked precisely this several days ago, and got all the info requested
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

My apologies.
My Internet provider is Demon and they had a major breakdown around 18th September after which news was not forwarded to me or other customers. This means that I never saw my original posting nor any answers that may have been given.
I'll have to try and use deja-news to recover the responses which I am most keen to read.
I must also apologise to those in this NG who DID reply to me for not having acknowledged and thanked them for their offerings.
ATB - Dave
--
David C.Chapman - ( snipped-for-privacy@minda.co.uk)
--------------------------------------------------------------------------
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I've now managed to retrieve all of the missing postings and would like to that those people who responded to my earlier query - subject as above - and gave such useful advice.
- Dave
--
David C.Chapman - ( snipped-for-privacy@minda.co.uk)
--------------------------------------------------------------------------
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.