Have you considered just using a credit card to Touch and Go? Seems the easiest way to pay the least amount. Here is what the Tfl.gov.uk website says:
If your bank card shows the contactless payment symbol, you can use it to pay as you go straight away. You'll pay an adult rate fare.
Many contactless cards issued outside the UK can be used to pay as you go for travel (overseas transaction fees may apply):
American Express (AMEX)
MasterCard and Maestro (some cards issued in the USA, Canada and the Netherlands aren't accepted)
Visa and V PAY (some cards issued outside the UK aren't accepted)
If you have a prepaid card, it may be accepted on our transport services. Check with your card issuer if you're not sure if your card is contactless or if it's rejected.
Using a mobile payment to pay as you go is the same as using a contactless card. You can make mobile payments with devices such as phones, watches, key fobs, stickers or wristbands.
You can use different mobile payments to travel on our transport services:
Barclaycard Contactless Mobile
If you use a mobile payment associated with a non-UK bank card, your card may not work or you may be charged overseas transaction fees. Check with your card issuer.
How to use
Touch in at the start of your journey and touch out at the end on yellow card readers using contactless (card or device). Only touch in on buses and trams. Find out more about touching in and out.
Contactless card over a yellow card reader
You can pay for someone else's travel with your contactless card or device if they're travelling with you. You need to pay for your own travel with a different card or device.
If you have a joint bank account, you can usually both use your contactless cards to travel as each card will be charged separately.
Find out why your contactless card might not work.
Pay the right fare
Always use the same device or contactless card to touch in and out to pay the right fare for your journey. If you don't, we won't be able to cap your fares. For example, don't touch in with an iPhone and touch out with an Apple Watch or contactless card.
A contactless card over a yellow card reader, followed by a device over a reader and a cross showing a clash. Contactless card followed by the same card showing the correct process.
Make sure you have enough battery otherwise you'll pay the maximum fare or might get a penalty fare
A mobile device showing a full green battery.
Watch out for card clash by keeping your contactless and Oyster cards away from your device when touching in and out so you pay for your travel with the right card or device
How much does it cost?
You can check your fare on our single fare finder or find out about journeys beyond Zone 9.
Travel as much as you like in one day or week (Monday to Sunday) and we'll cap your fares so you don't pay more.
You might see your payment on your bank statement as:
Create a contactless and Oyster account to:
Check your payment and journey history
Get email alerts if there's an issue with your contactless card which might stop you from travelling
Apply for refunds
Pay unpaid fares
If you're adding contactless cards for a joint bank account to your contactless and Oyster account, you need to either:
Sign up for one account if the cards have the same long card number and expiry date
Sign up for separate accounts for each card if they have different long card numbers and/or expiry dates
Download the app
Once you've created an account, download our free TfL Oyster and contactless app to manage your contactless and Oyster cards on the go.