I have been looking at old maps. On the 1909 Ordnance Survey, the name is
Mottingsden, rather than then MOTTYNSDEN.
View map: Sussex XXIX.12 (Burwash) - Ordnance Survey 25 inch England and Wales, 1841-1952
This shows the location of the
Manor House and the
Farm and
Oast
I used the Post Office search to find the addresses related to this place and they gave me the following list. I am not 100% sure that they are all distinct places, but all these will have been used as an address fairly recently.
The Post Office uses Bing maps to show locations of addresses on their website, and I used Bing initially to find the position of these addresses, but they had the Manor House in the wrong place.
MOTTYNSDEN
Lodge:
Google Maps Search for: 51.00155, 0.37124
MOTTYNSDEN
Coach House:
Google Maps Search for: 51.0013, 0.371
MOTTYNSDEN
Farm:
Google Maps Search for: 51.00252, 0.37344
MOTTYNSDEN
Oast (The Oast House is part of the Farm Building but the building is probably split into two now).
MOTTYNSDEN
House:
Google Maps Search for: 51.00372, 0.37263
MOTTYNSDEN
Manor:
Google Maps Search for:51.00323, 0.37395
It looks like the Lodge wasn't a Gate House type lodge.