insulating a blind space

[Thing]

I have a back room which is very cold, I think because 1/3 of it has its own roof space - it's one of those boxes that pokes out the back of the house. Problem is the pitched tiled roof space above it is totally inaccessible - in the loft the brick wall is all that is visible. What would be the best way to insulate the space? Seems possible to drill a hole from inside the loft into the space, or perhaps through the ceiling from inside the room, then inject foam or particles. It's not a very massive space, ceiling area only about 9x6ft. Is this a professional job or can I do a budget bodge by squirting some cans of expanding foam filler in there? I guess it would be easy enough to calculate the number of cans needed, but would it fill it or would just end up with a big blob around the filling hole and the rest of the space empty? I wouldn't want to have to get into removing a whole brick in order to check with a torch! House is about 90 years old by the way. If I can't fill the space the only alternative I can think of is putting in a false ceiling with insulation above it - but that's a bit naff and would spoil the look of the room, although the ceiling is high enough for it.

 

[breezer]

could you not make a loft hatch into the area? and as for foam, dont even go there

 

[Thing]

Probably could make a hatch, but I'm not sure if the space would be big enough to get into and do much in. Essentially this would be cutting a hole in the ceiling, insulating it with blanket or whatever, then repairing the hole in the ceiling. Sounds OK, but I was hoping for "keyhole surgery" if you know what I mean.