A breviate contains very useful information for identifying parliamentary papers. While selective, each item contains a full bibliographical record for the item and a brief but rich abstract of the contents. Reference materials specific to the Irish University Press set are found on that page.
In addition to the online database U.K.Parliamentary Papers, there is a rich set of documents in print and well indexed: The Irish University Press Series of British Parliamentary papers
The Parliament is expanding its online resources and including historial material as well.
The Hathi Trust contains digitized volumes of Parliamentary debates. The holdings are not complete nor listed in chronological order on each record. I have tried to note the ranges of dates available.