Damp /repointing

From what you’ve described it sounds more like condensation rather than a straight forward damp issue coming through the brickwork, but obviously it would need looking at properly to be sure. Small damp patches either side of patio doors are quite common with condensation, especially in flats where airflow isn’t great. If there’s only one air brick and the patio is right up against the building, that can also restrict ventilation which makes it worse. Repointing the outside might help if there’s actually failed mortar letting water in, but in most cases that wouldn’t stop condensation issues inside. If it was penetrating damp you’d usually see it worse after heavy rain and it would normally show more consistently through the wall rather than just around the doors. I’d say before anyone starts talking about costs it’s worth getting someone to properly check it, because if it is condensation then repointing won’t really solve it.