You can really get a refund for the Oyster Card at Gatwick Airport, so as quickly as you may be already at the airport. There is no specific Young Visitor Discount Oyster Card, you will want to purchase a Visitor Oyster Card earlier than your journey to London and then have the low cost utilized when you arrive. I actually have a questions for you regarding the contactless card and travellling with a 10 y.o. You can get the Oyster Card at the airport, most Underground stations, Tfl places of work, and so forth. Thank you for getting back to me with your useful answers to my questions. Your recommendation here offers some great help and an enormous time saver ,so glad I discovered you .