Gap under external doorframe to sub floor! What do I do?

[bliksim]

Hi all,
Any advise please?
Moved into my 'new' 1930s end of terace house and found a potential problem.
I cleared out some mud and weeds from the area in front of the bottom of the doorframe and found that there is actually a gap to the subfloor area! Water could therefore be coming in and I am not sure if there could already be damp down there or underneath the tiles.
I can actually physically feel the rafters underneath and after lifting a floorboard on the oposite site of the kitchen I found I could see light come through from the gap!
Can anyone tell me if this is normal in anyway??? Should I try and fill this up with cement?
I attached some picture.
Thanks!

 

[JohnD]

Looks like there should be a sill there - perhaps it's rotted away... in which case you need to deal with the damp, and any timber well treated with cuprinol green or similar.

You could possibly cast in a concrete sill if it can stand on the brickwork, but it needs to be mixed and cured well so it is hard and strong.

That concrete path outside is too high, so that water will run into the house instead of away from it.