Tri UK - West England, quite a drive from Oxford www.triuk.com
Its not clear why you'd want one though. Prices in the UK are generally
high, and goods are pretty much restricted to foreign bike parts, American
clothing, except of course Saucony who still make and sell both Tri kit and
running kit in Europe.
Assorted other shops can be found by checking the Triathletes-uk home page
http://www.triathletes-uk.org/links.html#commerce
++Mark.
The Sweatshop may do stuff to (they're primarily a running store),
they have stores in a few locations round london.
www.sweatshop.co.uk
cheers
Rob