About 2005 BECTA in association with NAACE produced some lesson plans for primary teachers which would provided useful websites for teaching. Whilst this service has since been discontinued, the lesson plans and the links to website are still available.  Why not look at the site and even better still download the document that has the internet sites listed. Some sites may no longer be available, however, you may be pleasantly surprised at the websites that are still there and this could save you hours of trawling the net.