Chelation is an amino acid called edta which is adminstered to the body thru an I.V. All heavy metals "cling" to it and the metals are excreted thru urine. It's been used for lead poisoning and other heavy metals since the 1940's.
The testing facility i spoke of is actually used mainly by doctor's (including my own), but they offer a few tests to the average citizen. The hair sample test is the same a doctor gives, but they generally follow it up with a urine test to be sure.
Don't know of any facilities in the UK, but look for doctors that call themselves anti-aging, nutritionists, ND's etc, then call and ask if they offer it.