I see from the census data for John that his estimated birth date is 1812. Using Familysearch, the closest match I could get is for John Cotterell baptised to parents John and Elizabeth on 31 Mar 1811 at Burlescombe (see https://www.familysearch.org/ark:/61903/1:1:NVND-T9G ) . From the map and I can see that Burlescombe is a neighbouring parish to Uffculme.