Thanks for all the responses so far guys, much appreciated. The rootsireland thread you've put up there Hallmark doesn't appear to be coming up for me, but I'll read into more about the site if I can as up until now I was taking the records on that site as gospel! So indeed if mistakes do occur regularly on those sites, I would need to know that.
Just going from that site for now though I can find 18 Sarah Campbell's born between 1860 and 1870 (she was 36 on the 1901 census so assuming she was born in 1864/65), the vast majority of them are catholic and there is indeed a Sarah Campbell born in Aghaloo (Roman Catholic) in 1868 (which I have attached). Its states here she was born on Mill Street, the street they are living on in the census.
All of the other Sarah Campbell's are in Cookstown/Coalisland/Castlederg, so this might be her. Although she's 3/4 years younger than stated on the census (she knows her own kids ages pretty well as their ages fit their birth certificates exactly, but not her own?) and most importantly according the RootsIreland website, she's catholic. However Sarah Campbell is a pretty common name and she might not be the only Sarah Campbell to be born in Aghaloo within those years.
Nevertheless I'm getting conflicting information here and its what I hate. I live in Omagh currently, do you I think I should visit the church to see if I can obtain any records and to check if Roots Ireland have made mistakes on this?
Regarding Lucenda Campbell I have found a birth certificate for her in 1880 in Ballymagran (parish next to Carnteel/Aghaloo) but her mother's called Eliza Thomson, so no direct relation.