We work with, and have helped inform a network of social science data archives across the world. These archives fall within the definition of trusted domain repositories and their data infrastructures follow the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. It is the mission of these archives to embed data into the research lifecycle to ensure that these data are published, shared, discovered and reused.
You can search for data using their online catalogues and the UK Data Service can help acquire data on your behalf. Some of these data archives provide access to popular harmonised cross-national survey series.
re3data.org registry provides an authoritative overview of hundreds of existing data repositories worldwide. The CESSDA ERIC provides a catalogue of pan-European data. Joining formal networks such as the International Association of Social Science Information and Technology (IASSIST) can also be a useful way to find support and identify other data providers