You can see pictures of Llanddewi Fach which are provided by:
You can see the
administrative areas in which Llanddewi Fach has been placed at times in the past. Select one to see a link to a map of that particular area.
Kain, R.J.P., Oliver, R.R., Historic Parishes of England and Wales: an Electronic Map of Boundaries before 1850 with a Gazetteer and Metadata [computer file]. Colchester, Essex: History Data Service, UK Data Archive [distributor], 17 May 2001. SN: 4348. Here is a gazetteer/finding aid plus a set of overview maps to accurately identify the position of parishes within the county
Family Search have an interactive map called "England and Wales Jurisdictions 1851" showing parish (and other) boundaries with optional background maps such as Ordnance Survey. There is also a Search facility, do read the guidance notes to get maximum benefit from this useful resource. See here for further background information to assist in the interpretation of this data
You can see maps centred on OS grid reference SO146453 (Lat/Lon: 52.099421, -3.248147), Llanddewi Fach which are provided by: