Over-fluoridation might be less of a problem in the UK than it is in the USA but there have been suggestions that all UK water should be fluoridated, and afaik it's still under consideration.
If you can get past your initial scepticism to this site, and read down the time line of this article on fluoride, you'll see that in the past year, the American Environmental Protection Agency have decided to prevent Dow from producing sulphuryl fluoride as a food fumigant:
"Victory! Ban on Sulfuryl Fluoride as Food Fumigant Granted
In 2010, the Objectors' attorney made several demands to the EPA to respond to the Objections, the Requests for a Hearing, and the Petition (Wallace, Apr. 2010, Aug. 2010, Nov. 2010). Just days before the Objectors were to sue for a response, the EPA finally announced that they granted all of their Objections.
According to the EPA's General Counsel for the Office of Pesticides, it was the first time in its history that it had done so.
The EPA announced on January 10, 2011, that it was proposing a phase-out ban on the use of sulfuryl fluoride. This was unprecedented and an enormous credit to the EPA's new administrator, Lisa Jackson, and to those in the Pesticides division who stood up for sound science and resisted the enormous lobbying effort by Dow.
Three days prior to this decision the Department of Health and Human Services used the fact that "41percent among adolescents aged 12-15" now have dental fluorosis as one of its reasons to propose a lowering of the fluoride level in fluoridation schemes. It's a great start, but the fight is far from over."
If you read the results of the rat tests and the science involved, you'll see that fluoride ingestion has the potential to be quite a serious problem.