See also the Politics subject guide for links to Journalism, Media politics, Fake news, and country specific resources
Note: in addition to some of the sources listed below, newspapers and magazines can be fruitful sources of ads. Refer to the News & Magazines section of the subject guide for details. The resources from Gale and Proquest are digital reproductions of the original publications, and have a filter for advertisements so you can limit results to ads. The filter is available for Gale Primary Sources, Proquest Historical Newspapers, GQ & Vogue magazines (both Proquest).
For broadcast advertising, we have access to Box of Broadcasts which covers mostly UK TV & radio stations. Recordings from commercial channels (such as ITV, Channel4) include advertisements, and you can search by company/brand to pick these up from the transcripts of programmes
You may be able to make use of existing datasets taken from social media. UK Data Service, UK National Archives and Harvard Dataverse are some of the places that host datasets. Third party platforms such as Google Social Search, Media Cloud, and Social Searcher can offer limited free data.