e-mori's Technology Tracker survey is always a good way for a quick UK internet stats fix. It is carried out bi-weekly interviewing "a nationally representative sample of adults (15+) across Great Britain. The Technology Tracker has been monitoring trends and developments in new technology since January 1997, the results of which are available to purchase as a single set or on a monthly basis."

For a pan-European perspective, try Pro Active International's figures. They'll also send you useful excerpts giving more details from their pan-European "Internet Monitor" product

Interestingly, e-mori say UK internet penetration is at 39% whilst Pro Active say it is at 45%. Either way it is fast approaching the PC / internet penetration plateau point of 50% that most people believe we'll see...

UPDATE: The reports linked to previously had broken links, so please use the Internet Statistics compendium (http://www.e-consultancy.com/publications/internet-stats-compendium/) for internet stats such as UK broadband penetration, etc.