I see that one of the sources extracted on Familysearch which records the baptism at Burlescombe of William to the widow Elizabeth gives a place of residence as No Mans Land - see https://www.familysearch.org/ark:/61903/1:1:6NXB-DC2L . If such things are of interest it should be possible to get an idea of where the Cottrell family may have lived.
The area known as Nomansland can be found on modern maps and on the tithe map of the 1840s which is available online by navigating the Devon County Council website at https://www.devon.gov.uk/historicenvironment/tithe-map/. This shows Nomansland to be very sparsely populated with only a farmhouse and a couple of cottages with gardens, amongst arable fields and orchards. The area seems be on the very edge of the parish of Burlescombe, within 100 metres of the Uffculme parish boundary, with the nearest centre of habitation at the village of Uffculme just down the road – easy to see why John junior would have said that he was born at Uffculme.