G.Mizer wrote to uk.transport.london on Tue, 26 Apr 2005:

Am I better off doing so at the USA side ( exchanging US dollars for
GBP) or wait till I get there and exchange it at the airport.

Do neither - just use your Visa or Master Card in any ATM, just as you
would at home. They do charge a fee, but it's minimal compared to the
convenience.

If you know a bureau de change that gives a great rate, then by all
means use it. There is one in Victoria Street, the corner of Victoria
Street & Ambrosden Avenue, that gives a superb rate, and I usually go
there for a few pounds' worth of foreign currency, to tide me over, and
then use ATMs as and when I need to.
--
"Mrs Redboots"
http://www.amsmyth.demon.co.uk/
Website updated 3 April 2005