The British Newspaper Archive is a subscription site which is available to use for no charge within the State Library of Western Australia (SLWA) building. It consists of millions of pages of digitised historical newspapers from England, Ireland, Scotland and Wales held at the British Library. You can register so that you can save searches, create lists and correct text in a similar way to Australia's Trove website. Select parts 1 -5 from the "content set" on the search page to search across all databases.
http://www.slwa.wa.gov.au/find/eresources/a2z/B/british_newspaper_archive
19th Century British Library Newspapers is the old name for British Library Newspapers Parts I-V. This is a subscription site which is available to use for no charge within the State Library of Western Australia (SLWA) building and from home for SLWA members. It includes newspaper titles 1800-1900 from all over the UK. Select parts 1 -5 from the "content set" on the search page to search across all databases.
http://catalogue.slwa.wa.gov.au/record=e1001959~S2
Richard Heaton has produced this handy index to British and Irish digitised newspapers.
http://freepages.genealogy.rootsweb.a.../~dutillieul/BritishandIrishNews.html
The National Library of Wales has digitised a large selection of Welsh newspapers up to about 1919.
http://papuraunewyddcymru.llgc.org.uk/en/home?