My family will be visiting London in June and I would like to use the 2 for 1 travel offers, but I am still somewhat confused on the details. We will be flying into either Gatwick or Stansted from Dublin and taking the train from London to Edinburgh when we depart. If I understand the promotion correctly, our train tickets from the airport into the city and from London to Edinburgh will qualify us for the 2 for 1 deals for our entire stay in London. Is that correct? And if so, can I go ahead and pre-purchase our tickets to Edinburgh now and just print them up there (to meet the paper ticket requirement)? I have heard that the trains can fill up and we will be traveling on a Saturday so I don't really want to wait until we are in London to buy our outbound train tickets. Thanks!
The 2For1 FAQ says: "If for example you are buying single tickets, e.g.Advance tickets to London for a one-way journey on a Monday, and Advance tickets for departing London on a Friday you will be able to use the vouchers during the Monday-Friday period, provided you show both outward and return tickets (remember to tell the train company staff that you need to keep your outward tickets!)." So your understanding is correct, but make sure you do not surrender your ticket when you arrive into London which means talking with the barrier staff. If you put the ticket in the barrier it is quite likely just to be retained. East Coast do offer print-at-home tickets or you could collect them at Stansted or Gatwick. PAH tickets require that you have the identification document you quote on purchase being available for inspection for rail (but not for the 2F1).