Simple detail to prevent water ingress above door?

[Tony K]

Evening all. 

In the garden of my SB I have built a home office. It's single skin block, which I will wrap in breathable membrane before cladding.

 

I have built a feature brickwork projection around the doors. There is a gap at the top between the brick and the block, as you can see.

 

To protect this I planned to get a bit of arris rail, wrap it in either lead flashing or roofing rubber, and fix it over the top of the bricks. I would then dress the membrane down over that. 

 

Thing is, that wouldn't give me a drip bead. I'm not sure if that matters. I might be overthinking it!

 

I have thought about using a pvc windowsill over the top, but I'm not sure how I'd address the junction between the sill and the block wall. In any event, I'd want a grey or black one and for the size I need I'd be paying more than seems sensible.

 

How would you treat this area?!

 

Thanks