Where the roof meets the wall

In U.K. You buy a roll of semi flexible stuff called flashing to seal one to the other. I've tried explaining this in Portuguese building suppliers and they look at me like I'm an alien... solution? Fill the gap with mortar and then cover with the rubbery paint stuff they sell and include a layer of fibreglass tape. There's still a metal trim to go on the raw edge of the roofing to hide the foam insulation.