You can maybe check if it is coming from sunroof by rolling the carpet away and getting a hose on the roof ( or take it through a carwash ). There should also be drains in the bottom of the scuttle outside below the windscreen ( the plastic bit by wipers with slots on top that takes water from windscreen ) these allow water that collects in the plastic housing to drain down the front of firewall in engine bay, if you open the bonnet and pour water into the vents you should see it drain away and run down the firewall, the drains can get clogged by leaves and moss, have any of the grommets on the firewall been disturbed - ot may be some plastic bungs missing. The only other thing is a leak in heater matrix, but you would have seen water level in expansion tank and radiator itself drop, and also a strong smell of anti-freeze in the car. If there is a ford near you try driving through it and see if water is coming in through floor. The usual thing with Jazz is water in the boot due to failed sealer on roof strips, don't know if water can get past at the front of car and trickle down 'A' pillar. The other thing is the sealing around the aerial base....
You can get condensation in the car in colder weather by NOT using the aircon as the inside of the car gets warm and humid and the metal body is cold.