Where can i buy a travel towel in London?

[LittleStar1]

hi,i'm looking to buy one of the light weight travel towels before i go on holiday next wednesday, but ive left it a bit too late to get one off the internet. i've looked around online but cant find any shops that sell them. Im sure there are loads i just cant think of any. if anyone could help or suggest some places that would be great, thank you all