Hi I will be traveling to London next week for 7 days. I plan to buy a 7 day travel card on oyster. Can I add additional money to cover the heathrow zone 6 to knightsbridge zone 1. Do you how much this extra is--i will be arriving around 10:30-11:00 am morning. thanks in advance.
Yes, you can load both a 7-day travelcard and cash for pay-as-you-go on an Oyster card. With an Oyster card the off-peak fare (after 09:30 on weekdays and anytime on weekends) for a single ride from zone 6 to zone 1 is £2.20. FYI, if you bought a single ticket, the fare would be £4.00.
If you aren't traveling alone, check out the 2-for-1 deals offered by National Rail here. To use the vouchers you must have paper travelcards bearing the National Rail logo which are sold only at National Rail stations, not tube stations.