I've seen the Oyster card is prepaid.. but somewhere it indicates you can have an unlimited pass... ? Is there a choice on the machine where you fill your card? Thanks
There isn't an unlimited Oyster, you are referring to a travelcard. But TFL made the travelcards a lot more expensive than the daily cap on the Oyster so for most people using the Oyster is more cost effective. The daily cap in zone 1-2 (all of Central London) is 6.40£ no matter what time of day on the Oyster, the travelcard is currently £12. If you don't use the tube or buses enough to cap out on the Oyster, you only pay what you use. Based on the single fares, you go over the cap on ride #3.
For your 5 day visit, you might want to start out with £20 and then check the balance on day 3 to see if you need to add more. Unless you go outside zone 1-2, £20 should cover you for the full three days.
Hi Isa, the easiest way is to simply top up your oyster with a little money. Once you reach the amount a day ticket (you can obviously buy those at the counter as well), it won't get more expensive. then it's kind of unlimited for that day.
For me that makes more sense than buying a day ticket in advance, since you might not end up driving as much as you thought.
You can add a travelcard (7 day, monthly, yearly) to an oyster but you must register it and I think you need a UK address to do this. There are Visitor Oyster Cards but it looks like you can't add travelcards to these and they just come prepaid. There are paper travelcards you can buy but they are more expensive.
If you have a friend in the UK then you could ask them if you could register it to their address. Otherwise a visitor oyster card is the way to go.