I would highly recommend getting a professional local roofer/tradesman to come and look at the problem as this could be from gables, flashing, broken tiles, guttering or the window seals. Your tradesman should be able to find and fix the problem

Hi I’ve generally found that on terrace house 80% of the time it’s poor air circulation and bad insulating that cause the damp spots I would advise opening a window slightly and washing the damp spot down with warm water with bleach to kill the mould of. And after a few days you’ll soon find if you need your guttering looked at

First start with ventilation is there any if no consider putting air vents in if yes have you checked to see if the gutters are blocked if they are not blocked if could be loose tiles on the roof or do you have wall cavity insulation this can cause damp as it bridges the gap between the 2 skins of wall and not allowing the wall to breath properly

would check the roof line, gable wall insulation in the loft,gutter, roof tiles. flashings, window seals for defects as this could be a few different issues that are combining to create this.

good luck Alex