I will be traveling to UK in a few weeks from US via YYZ to LHR and was wondering what is the best way to obtain UK currency. Last time I was in UK several months ago and was not prepaired at all and had to exchange US dollars to UK pounds at LHR at one of the exchange places. However, I have found out it cost me an arm and a leg to do it in order to take a cab. I have looked at some options, one of them is to buy from Travelex online and have pounds shipped to my home prior to departure, but the rate is not the best plus $9.99 delievery fee. I will not need to exchange a lot, but up to 200 GBP would be nice. Open to suggestions.