You will be very unlikely to find the marriage record and baptism details on line if they were RC I'm afraid. Only a minority of RC records are on line.
I'll second that and third it for Preston. Many of my maternal ancestors were in Preston in 19thC. I had to buy marriage certificates.
As far as I know, Preston wasn't included in transcriptions of registers published by Catholic Record Society in their journals.
List of Catholic churches in Preston + dates & location of registers are on GEN UKI website. Select a church to see dates of registers and map location. There's an option to see all churches of a denomination on a map of Preston. Each denomination has a coloured marker. Can select appropriate denomination or coloured marker.
https://www.genuki.org.uk/church_list/1815 Baptism and marriage registers of St. Walburge's from 1853 + burials from 1891 are at Lancashire Archives, according to GENUKI.
Church Registers Guide on Lancashire Archives catalogue, arranged by denomination. Roman Catholic church registers list is in alphabetical order of place.
https://www.lancashire.gov.uk/media/67392/P.pdfInformation about St. Walburge's Church, Preston on Lancashire Past website with links to other sources.
https://lancashirepast.com/2016/12/20/st-walburges-church-maudlands-prestonSt. Walburge's Church is on Facebook.