Are you sure this is fair on your friend? How long is she going for? If it's just for a few days you may well be asking her to take time out of her busy itinerary to go to somewhere that's not even on her schedule. She then has to account for the weight of the coat in her luggage when she comes home, what if this would take her over her weight allowance? Would you be prepared to pay any excess baggage allowance? It may also take her over her duty free allowance, depending on what else she buys over there (there is a limit of £390 worth of goods that can be brought in duty free). Again, if she goes over this limit would you be willing to pay the excess duty? Then what happens if the coat doesn't fit? Would you hold her responsible if if was, for example, too small? I would double check with your friend that you are not asking too much of her.