Just want to confirm my thinking is correct, and still applies for now (Spring 2014). We are flying into Heathrow and staying in London for a week- we'll be using the tube and buses primarily. If we go to a rail station (Paddington Station is fairly close to where we're staying) and get a travel card printed on National Rail paper...we can use it for tube/bus travel and to present (for length of stay if we get the travelcard for the full 7 days) for the 2 for 1 deal. We don't have to go back to the train station every day to get a new card to use that day for our admission. (and also, our 10 year old doesn't need a ticket for the tube/buses- but our 12 year old will?)
Does that sound right?