Catholic baptism / marriage / burial Records are not that readily available on line yet.
Most voluntary researchers only have access to a subscription site and whatever Parish records are licensed / purchased and placed on the site, freebvmd .org.uk and sites such as yorkshirebmd.org.uk / familysearch.org together with ant other free to use site they know of.
You could check the Army records or even the local Record Office to see if they hold the records. this info
If you are failing to get the record via the Catholic 'Diocese' others like myself will also struggle.
Your best option is to purchase the entry from
www.gro.gov.uk this is £9.25 sterling per certificate