Re. Mary Carew, my thought is that she is more likely to have been born at Bickleigh than at the other locations. Bickleigh and Uffculme are just 12 and a half miles from each other, which makes this more likely.
The Bickleigh baptism is on FMP:
http://search.findmypast.co.uk/recor...hlights=%22%22
I think you need to find the marriage between Henry Cottrel and Mary. This may mean a visit to the RO.
Another reason I think the Bickleigh baptism to be more likely than the others is that the other suggestions are for girls baptised much further away. I know people did travel more than we would think in the 1700s, but I grew up in East Devon, and I know the area around Uffculme/Bickleigh/Sidbury very well. Even in the 1950s there were farmers who hadn't been any further than Exeter, and some not even there! What was Henry's occupation?