Ancestors in Kilbeggan, WestMeath ?

I have been researching my Irish roots for over 20 years.   I have discovered that my Irish GGgrandfather and GGgrandmother immigrated from Ireland to St. Helens England somewhere before 1851 where they appear in the census of England.   

My GGrandmothers name was Margaret Neville (b. 1829) father Robert Neville.  My GGrandfathers name was John Lilly.    They marriage in England (1847),   its not certain whether they came over from Ireland together or separately.    I found that they were from WestMeath, because we found a sister of Margaret in the same town,  and on one of the census records from England, it stated that she was from WestMeath Ireland.      I then searched the rootsireland.ie,  and found a Robert Neville, married to a Sarah Carey with all the childrens baptisms that matched the sisters of Margaret (Ann and Mary)  in Kilbeggan.  Her sisters names were known because she was living near them in St. Helens after they immigrated over there. 

I'm looking for any information on Neville (Nevill), Careys and Lilly's in WestMeath or surrounding towns of Kilbeggan.   Or any information how I might find more out from the Catholic records in Kilbeggan. 

I have almost no information on my GGrandfather John Lilly (b. 1821),  except that his fathers name was  Denis, and his mothers name was possibly Cathering.    He had a brother or cousin named James and Joseph,  that also immigrated over to England after the famine. 

Thanks in advance if anyone has any hints that might help!

angela napolitano