I'm having trouble deciphering the best option for our extended family this summer(July) in London. We have 5 adults and 4 kids (ages 15, 15, 14, and 10). We will be 7 days in London but hope to make day trips to Ickleford (4 of the adults spent several years living there and want to revisit), Stonehenge, and possibly the Harry Potter studio. The best I can come up with from looking at the TFL site is to buy 4 Adult Oyster cards, three 11-15 kid Oyster cards and one 5-10 kid Oyster card. This appears to be the best way to get the best price on any rail travel outside London. The TFL site also says that PAYG travel within London's travel zones will be capped at the daily Travelcard rate, so it seems like there is no advantage to adding a Travelcard to your Oyster card. And it also seems that there is no way to take advantage of any of the 2for1 discounts using the Oyster card. Do I have this correct?
Thanks for any help!