Parliament UK offers a number of resources to researchers including:
Search parliamentary material to find publications and records of parliamentary business, classified by staff of the House of Commons Library
Hansard Parliamentary Debates House of Commons debates from 1988- and House of Lords from 1995/96- from the official Parliament website. For the period 1803-2005 see the very useful Hansard Corpus, which offers advanced semantic searching, and the same period is also covered by the House libraries - Debates 1803-2005
See also the interesting Hansard at Huddersfield research project & interface to Hansard, examining & visualising patterns of language use (1800-2003)
House of Commons Library research briefings the full text of Research Papers from 1998, compiled for Members of Parliament by the staff of the House of Commons Library.
Parliamentary Office of Science & Technology (POST) carries out research relevant to policy & interviews stakeholders. Its publications (notes, briefings, etc.) are freely available
UK Parliament Web Archive aims to ensure that historic content from UK Parliament (see above) will remain available for future researchers
For information & sources on the Northern Ireland conflict see:
CAIN Web Service guide to websites
Divided Society : Northern Ireland 1990-1998 (Linen Hall) offers much digital material
Accounts of the Conflict (Ulster University) digitised oral histories
Some useful guides to sources for UK political research:
Cook, Chris. Sources in British political history, 1900-1951. 6 volumes. London : Macmillan, 1975-1985. Z 2020 (Floor 5)
Cook, Chris. Routledge guide to British political archives : sources since 1945. London : Routledge, 2006 CD 1041.R6 (Floor 2) and ONLINE