I had a customer with this problem, probably worse. The loft was dripping. I put 2 or 3 air vents in the wall to move air about. This seemed to do the trick.
It will be fine. The house will have had plenty of rain, snow gales etc over the last 100 odd years without much trouble. I am no expert and haven't seen it, but don't worry and turn the water main off and electric while your not there.
