London underground

You can just use your contactless bank card to tap in and out.

Get the Citymapper and TfL go apps very useful

If the kids are under 16 you should get a travel card for them.

How old are the children?
Under 11s used to be free if accompanying a paying adult. Well, they were when I left London 4 or so years ago. You can't go through the usual barriers though you have to be let through by the guard, usually up one end.

For yourself just use your bankcard.

Tap on, tap off with your bank card ...under 11s free

Oh yes under 11s go free with a fare paying adult but 11-16 need a card otherwise you'll end up paying full adult price. My 6 year old granddaughter proudly has a Zip card she can swipe on the gates.

You can't get railcard discounts on the Underground.
As others say, just use your contactless bank card and remember to tap in and out at the barriers. The fare will be worked out after you finish your last journey. There is a fare cap which varies with travel zones, times etc. I think it's less than £10 for 24 hours in zone 1.

Remember its probably easier to walk around zone 1 than get the tube. Check out Google maps for a route.

We went to London last weekend and used the Tube a lot - we tapped our Debit Cards in and were charged 10p a journey- Bargain!

But you can't do that for children

Have you got a bus pass? That works on London buses and children under 11 go free as on the tube. (11s to 16s need a zip card.)
You see so much more from a bus.

For you, if you have a buss pass for wherever you live, you can use it to travel free on London busses. Not on the tube though unfortunately!

Very well integrated transport in London - you can switch between buses and tube and system tracks you and rolls up different journeys so that you never pay more than the cost of a travel card. Just make sure you use the same card each time. Under 11s still free.
You can also ‘tap on and off’ the Uber boat that zips up and down the Thames - great fun!

If you have a senior railcard and an oystercard you can get them linked so you get discount on the fare. You cannot do this online you have to ask a member of staff a tube station

You can only use for bank card for yourself. Any other adult must use their own bank card. Why not go on the bus and see some of the London sites

If you purchase an Oyster Card, link it with your bus pass and load it with an amount of cash you get all the discounts. On your exit from London go to a station and ask at the ticket office for a refund of what is left of your credit on the Oyster card.

A schoolfriend who later worked in central London always travelled by tube & didn't know one area from another. I travelled Essex to SW1 Victoria by annual bus pass & could tell you exactly what was above us when on the tube (when late going to work) as I knew most of it like the back of my hand.

Romola

Have you got a bus pass? That works on London buses and children under 11 go free as on the tube. (11s to 16s need a zip card.)
You see so much more from a bus.

Yes, we always travel by bus with our grandchildren if we can, there's so much more to see that way and you can get off if you see something interesting. Obviously if you have longer distances to travel it's simpler to use the underground, though some changes involve more walking and take much longer.

Jan135 is right, you CAN get a discount on the tube with a railcard. You have to link it to an Oyster card. Just ask a member of staff and they will take you to an Oyster card top up machine to link it with your railcard- they have to do it, you can’t do it yourself but it’s quick and easy. I do it every year when I get a new railcard.

I linked my senior railcard to my oyster card, I had help. From a member of staff. I had had the iystercard, for ages though. You need a different card for doing tap in tap out for each person (if not using an iystercsrd) but I understand that paying with your phone counts as a different payment method even if it is the same card as the physical.one. There is a cap on daily costs if you tap on tap out. I guess there is one on an oystercard maybe. Need to check that
Niw I already had an oystercard but there is a cost to it, so you need to work out is it worth getting an oystercard to get the discount on your railcard, will you be using it iften. And you will have some Mindy loaded on it unless of. Course you've managed to. Put the exact amount you'll ve spending
And if you've an English bus pass obviously you can use it on the bus. Even though this can take a bit longer, I personally like to do this, so I can enjoy the view. I look up the suggested routes on Google maps and /or transport. For. London and use that to tell me where to get off off so I don'tm iss my stop, and where to pick up the next bus. Sometimes tube is an easier journey, sometimes a mix of both.

I stand corrected.
It sounds like a faff to get the discount added if you're only visiting for a day.

I'd recommend walking if you're sticking to Zone 1 tfl.gov.uk/modes/walking/