Re slating a semi

[cyc7510]

Hi, we are re slating our house which is a semi.
The adjourning property’s battens are 19mm thick. Our new batten is 25mm.
We (think) it will cause problems if we just install the slates over the step. Will this be an issue?
We are thinking of planning the top of the battens across the two rafters.
Or the easier option, notching the underside of the battens taking out the step over two battens, 3mm and 6mm where they meet the neighbours.
Is this is right way? Or you have a better suggestion?

 

[DAZB]

Either way would work well and it is either that or bonding gutter but if you can avoid that then the result always looks better.