i usually buy some currency for whereever i may be about a week before i leave
years ago i tried playing the currency exchange rate game and it just becomes a hassle
sometimes you win by buying early, sometimes you lose
so i just deal with the rate a week before and live with it
as for a credit card in the uk, from what i understand, unless you have a permanent address there, you may have an issue getting one as a temporary resident
(unless you're there with an...