[Fen]

I understand your concern.
Why not make a "sausage" filled with compost or similar and wrapped in bin bag material and taped together. Lay it along the outside base of the door.

[Pimento]

Thanks, Fen, good idea - that would certainly help!

Pim.

[Annen]

You might have sorted your door by now, but I've found strips of foam pipe lagging amazingly useful for plugging gaps in my hut, couldn't you fiddle something like that for the winter?