leaking roof - updated

[Rechar]

The house i am currently living in is slightly lower than the neighbours (approx. 2-3feet) so our roof keys into their wall (i forget the technical term for this, sorry!).

I was doing some work on removing wood panels from around the window and found the plaster and wood where soaking wet behind. A quick glance when it rained showed a lot of water coming in through the cavity. I decided to investigate and removed a section of the ceiling to gain access as its right in the corner.

It seems like tarp has been eaten/ripped away, revealing a large amount of expanding foam behind (underneath the tiles) and this is where the water is penetrating.

A few years back we did have the facia/soffits re-done which might be a cause for this gap.

Obviously the tiles above this section are leaking somewhere (are a few leaks "acceptable"?), i think this might be down to the last truss which has a slight 5-10 degree tilt towards the neighbours slowing opening up gaps, though it could have been like that since installation as all the others arn't level either...they arn't the most amazing houses.

I've attached a few pictures of the affected area to help illustrate what i am seeing, sorry if they are poor quality....

http://i38.photobucket.com/albums/e101/Rechar/DSC00035.jpg
http://i38.photobucket.com/albums/e101/Rechar/DSC00037.jpg
http://i38.photobucket.com/albums/e101/Rechar/DSC00036.jpg

So, long winded explanation aside i've a few questions...

What would be the required work to fix this problem to an acceptable level (primarily meaning no leaks)?

Is it a technical process? I love to dabble in all sorts of DIY but have never attempted roofing (epilepsy and heights...not a good combination, but this side is above a garage so only a maximum fall of about 7feet...which for me is acceptable *grin* ).

If not, as i'm a voluntary worker cash is hard to come by so i need to find a good deal, what sort of price would i be looking at?

Could the leaning truss be remedied (or stopped from getting worse) with noggins bracing it against the neighbours wall?

Hopefully i havn't rambled too long, thanks for you time.

*EDIT*

I decided to ferret around and rip away the underlay...and the building foam. Its clear what the problem is at least now!

So, i have a snapped tile, and apparently a half missing batten. Whats worse...they didn't even bodge the bodge correctly, about an inch of the crack was left unsealed to the left of the picture.

[datarebal]

Looks like the tile is a Marley modern.
Repair will be easy simple push up (by pushing hard on the bottom of a tile) a couple of tiles side by side over the damaged tile take out this tile and a few either side of it allowing you to repair the felt and batten.
slip the tiles back along with a replacement. job done.

Get it fixed before your trusses rot out then your in deep s**t

__________________
New Forest Roofer

[Rechar]

thanks very much for your help.