This report from Comscore is a must-have for anybody interested in the demographics of how Brits use the Internet. Lots of stats about the older age group.
However, like most (all) research companies, Comscore still has this '65+' segment that includes a wide range of different types of people. To be honest, it is next to useless.
Still here are a few of the charts - there are many more in the full presentation. Definitely worth downloading. Dick Stroud