Hi Lesley
Thank you for your query. It is helpful to include information concerning which sources you may have already used so others may further your search. You have good information to start with however to find any existing church records for Catherine you will have to find an exact place of origin for her in Cork (e.g Townland or Parish).
You know a good deal about the charges that she faced and her transpotation again it would be helpful to know what sources exactly you used. Have you referenced Prisoners' Petitions and Cases, 1788-1836: these consist of petitions to the Lord Lieutenant for commutation or remission of sentence, and record the crime, trial, sentence, place of origin and family circumstances.
It could be useful to search the UK Archives:
http://www.nationalarchives.gov.uk/records/looking-for-person/
These records were microfilmed and a database was presented to the Australian government and can now be found in many State archives. The NAI retains copies and the database, in particular, can save a great deal of time and effort. www.nationalarchives.ie Early convict arrivals records, making up some of the gaps in the NAI material, are also online at www.pcug.org.au/~ppmay/convicts.htm (Irish Convicts to Australia 1791-1815).
Here are some other websites that may be of help to you:
http://www.genealogylinks.net/uk/ireland/cork/index.html
http://www.irishtimes.com/ancestor/browse/
http://www.nli.ie/en/family-history-introduction.aspx
http://ifhf.rootsireland.ie/?gclid=CKLT_Pa4wrUCFYUf4Qod4EoAGg
Lesley we hope that this information is helpful.
Kind regards,
Genealogy Support