Bob,
I would suggest a liquid applied membrane roof material applied to the felt and up onto the brick/stonework. You'll need to address the hole in the bricks first though.
check out www.belzona.com, 01423 567641, they've a guy in your area.
Nick from Belfast
Having recently bought a house, the attic has a velux window in the roof tiles. Is there any requirement for planning permission as this is still an attic and not a loft conversion as still use ladder to access when required? Is building control to have been contacted?
The job looks to be...