Hi Dennis.
Is the roof a new one you have just done?
if so the best method is to use somthing called a Verge Tile.
Here is a lnk to a picture
http://www.manthorpe.co.uk/SiteData/Root/image/BuildingProducts/DryVergeSky.jpg
Thes tiles are available to most commom tiles.
www.simplybuildbetter.co.uk
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix roofing.