i had something similar it ended up being the grommet that held the bonnet release cable in the bulkhead, (up underneath the steering column) it had come out and just needed pushing back in, you can also have problems with the seam sealant cracking underneath the front wings where they meet the A pillars, this can cause leaks in the cabin as well. i stuffed a load of tissue paper up underneath the steering column then sprayed the car with water for a while then checked which bits were wet to try and see where the leaks were coming from.