If its the charge cable that you need, then pretty well anywhere will have them in stock...PC World, Tesco, etc. Ebay as well, but you will have to wait a couple of days.
Do you have a proper computer hat you can use in the meantime ?
I always use Amazon for things like that.
I found that the old style inch wide thingy sometimes didn't work if you bought a cheap non-Apple one, but with the new miniature charger opening they seem to be fine and not expensive.