[QUOTE=""]
I believe that cash withdrawn from an ATM with a credit card will be treated as a cash advance and subject to immediate interest charges.<<<<<<<<<<
[/QUOTE]
Gawd, never do that. Just your debit card. But use the CC for most anything.
[QUOTE=""]
Get an Oyster card and don’t forget to tap in AND tap out!
If you are travelling with someone else, each of you can opt to carry cards isued by different entities. On our recent trip to Spain, between us, DD, MIL, and I had debit cards from three different banks/credit unions, two different MasterCards, two different Visa cards, and two different American Express cards. Before we left home, we made sure to get PINs for all of the ones that we could.
Interestingly, the Delta Airlines Gold American Express Cards have chips, but no PIN capability. I had to sign old-style. Which I did for the car rental. When I used it to buy train tickets, they just ran the card and didn’t give me anything to sign. When I asked, the agent said that I didn’t need to sign anything! I hope that was because my card matched the name on the rail line’s own Senior Citizen discount card I had just got the day before, and that they don’t just do that for any one who hands off an Amex card 
“Gawd, never do that. Just your debit card. But use the CC for most anything.”
Well, if your ATM card gets sucked up or compromised in some other way, that CC will sure come in handy for taking out cash. It happens.
But, yes, only for emergencies if you can’t access cash via an ATM card.
Schwab refunds ATM fees AND has no foreign transaction fees. We use that as needed for ATMs when we are out of country, as well as CCs.
I can’t remember which one of our common Visa cards has no international transaction fees but is fairly common. I think Capitol One types may have that. It is good to have two different credit cards. One of ours has different numbers for each of us on the same account. Very easy to have cards widely used (and with no annual fees) in the US that can be easily used abroad.
Check on Master Card and Visa from various sources for a card you can use easily here and abroad instead of the obscure for here Barclays.
CapitAl One is an excellent no international fee card. I get the lowest possible exchange rate at my local bank, so I do not understand the advice to wait until you get there. I like having some in my wallet as soon as I arrive and I generally also have some notes and coins left over from the last trip. Are there really any bank ATM cards these days that are not part of an international consortium? Never had a problem getting cash from an ATM. Well, one time in Rome, but we just walked up the street to the next one.
DH and I just got back from our first trip to London. Send me a PM if you have any questions. We were there a week and did typical tourist things and one day trip to Cambridge.
As to money, we worried too much about this. We ended up exchanging money at the airport before we left. It wasn’t the cheapest (a fee and a bad exchange rate) but it worked and we didn’t have to worry about it later. If we had planned ahead a bit more we would have done it at a local bank before we left and in hindsight an ATM when we arrived in the city would have been fine. They were easy to find, had no extra fees and we didn’t need any cash the first day we were there, even for a taxi. We started with maybe 60 pounds, never needed more, and spent the last twenty on souvenirs at Heathrow while we waited for our flight home. There were a few places we needed cash when we were just buying a sandwich or coffee and the total was below their minimum for a credit card.
our ATM card is through a credit union. They waive the first two outside ATM fees, and the network includes plus and visa and those were widely available in London with no fee, we just never even needed them.
a credit card with a chip will work most everywhere. The transactions would have been a bit simpler with chip and pin but we didn’t ever have a problem.