Oyster Card versus Travelcard for London day trip

[lostWingnuts]

Travelling to Londonby car mid April.
Possibly parking up at Harrow (on the hill) and tubing into a Travelodge in Docklamds to drop luggage, then a bit of sightseeing probably the Portrait gallery, then 02 concert later that evening, travel back to hotel, then tube back to Harrow next day.

Can't figure out how much to credit an Oyster card for!

I think £10 would cover it but a day travel card would work even better as you might forget to check in & out with the Oyster card. Who will you see at O2?

as a regular visitor to London who tries to do it on the cheap:

• the travelcard is one price and then it doesn't matter how often you use it. BUT it only lasts for a day.
• the Oyster card is pay as you go and works until you use the credit - there is a daily cap so you won't pay more than the equivalent travelcard. You can do much better on the fares if you avoid the peak times, which means you must not be touched in between 0630 and 0930 and 1600-1900 Monday to Friday. At the weekend it is all off peak.

it's not hard to remember to touch in and out at the station, but DO know what the fare should be and read what the display says. I got a 60% overcharge on mine. If this happens raise a complaint with TFL for a refund.

as it appears you are doing a lot of running around on one day, buy a travelcard for that - it lasts until about 2am. (That means you can get a bus or tube as much as you like) Then for the return trip next day, put a fiver on the Oyster card if it is just that one journey and is off-peak. Alternatively, as Harrow on the Hill is zone 5, put £15 on the oyster card to cover both days and have a bit left over for next time.

here are the fares for 2014:
www.tfl.gov.uk/assets/downloads/tube-dlr-lo-adult-fares-jan-2014.pdf