Outrigger with gable end wall

We’re in the process of building a house with a contractor doing the construction of the walls and roof-framing, per the architectural drawings (as per the left-hand image). We’re now at the point that the roof can be started in the next couple of weeks, and had been studying what needs doing, so am comfortable with what needs doing for breathable membrane/counterbattens/battens/tiles/ridge and insulation.

My big question was how to “fix” everything at this wall end, after some research I can see that outriggers are used to get this floating rafter (right-hand picture). However, all the cases I can find have wooden gable ends whereas I have this solid end.

Is this the right idea?
Should the outriggers be 50mmx250mm?
Should the outrigger spacing be 600mm centres?
What size should the overhang be? (anything up to 600mm, or do I need to calculate it based on the tiles I’ll use)
How are the outriggers fixed to the rafter (I’d struggle to even get a nail in 50mm gap, let alone a hammer :slight_smile: )

Rafters are 50mmx250mm
Wall is 500mm aerated concrete blocks
End rafter’s have 50mm gap from the wall

20 days late, but the outrigger needs to be tied into the rafter before the barge rafter. In other words, it needs to be into the 3rd rafter, notched into the last rafter on the wall, then into the barge rafter.