The IGI or International Genealogical index has been compiled by the Latter Day Saints (Mormons). It is not complete for many parts of the UK because not all parishes have been happy to give access to their registers.
The IGI is online http://www.familysearch.org/
but you need to realise that the entries marked submitted may be very inaccurate. Those extracted directly from registers may also be wrongly transcribed.
The Latter Day Saints (LDS) also run various family history centres and you may find one near you.
People able to research in the UK would tend to visit the local Records Office for the area of interest and look at copies of the original registers on microfiche. The LDS have some of these in their centres too and I believe you can order particular parishes and have them there for when you visit.
OK so this is how you go about it.
Online you can hunt for ancestors going back through the censuses from 1901 to 1841. These can be found on Ancestry if you are a subscriber or Findmypast http://www.findmypast.com/
or Origins http://www.englishorigins.com/
You can also hunt on the IGI and it helps to understand the system. Please readhttp://freepages.genealogy.rootsweb.com/~hughwallis/IGIBatch...
but remember that many parishes are not in the index or are incomplete.
I didn't quite understand your reply. Were those Rowes of Uffculme definitely yours? If so how have you reached that conclusion? What evidence have you found so far?