Buy a cheap sim card in London that also works well in the E.U.? Suggestions?

You will just need to check with the carrier you talk to in London. I used to get Vodaphone SIMs, they worked well everywhere, but most any major carrier will. Just assure that you will have coverage for the EU. You are correct, that after Brexit, carriers are not obligated to having free roaming in the EU, but some have kept it as a sales feature, and most offer it under different packages.

Another option, if costs look to be excessive, is to just get through London, and pick up SIMs in Paris.

Check this "prepaid SIM" wiki for the UK to see which carriers might offer EU roaming. But yeah, at worst, you buy another SIM when you get the Paris.

https://prepaid-data-sim-card.fandom.com/wiki/United_Kingdom

Google Fi is worth looking into. You need to buy the SIM and activate while you are in the US, then in Europe the rate is $10/GB. Actually we liked it enough that we dropped our more expensive T-Mobile plan and use them fulltime since they only charge for cell data you actually use and here at home we're almost always around WiFi at home or in the office.

I use a UK Giffgaff SIM that also has EU data. I'm in Paris at the moment using this for roaming and it's fine. It's £10 for 15GB, and you can use 5GB in EU roaming.

I guess this is a problem (admittedly a minor one :-) ) with starting a trip in London, post-BREXIT.

While we are starting in London, we will be there for only 5 days and then will spend 5 weeks in the E.U. And we will also be returning to the E.U for another two weeks around Christmas.

So it would be better if we could get a card that is "native" to the E.U. with foreign roaming in England. I'll have to see if I can find a Vodafone card there.

There are four of us, so I expect if we have to, we could buy just one SIM card there and then buy more in Paris.

And I forgot--visiting Greece 6 months ago I got a Cosmote card there--I need to look at whether that is still valid and might work in England!

I bought an Orange sim card on Amazon for my husband's phone and it allowed top-ups if we'd needed it (our trip was less than 14 days). I had an Orange eSIM. Orange is based in France and I was able to use it in Iceland, UK, and France. It mostly worked great, the data was perfect but sending texts only sometimes worked, especially when trying to send messages back home.

We used Whatsapp to communicate with each other when we split up for the most part and with calling back home.

I didn't realize I could just get a SIM card for Europe on Amazon. Too late for me know since we're about to leave.

I was just looking at the U.K web site for Vodafone. Their "pay as you go" plan does NOT cover most E.U. countries. It only covers Ireland, the Isle of Man, Iceland, and (for some odd reason) Norway.

It is possible to get E.U. roaming as an "add on" but this is relatively expensive, like 10 pounds for 8 day. So maybe OK for a short trip, but I'll be in E.U countries for 5 weeks and having to renew the roaming package every 8 days will be annoying and a needless expense. It's probably most cost effective to just get the cheapest "pay as you go" plan for London, and then get a something new in Paris.

But if anyone has suggestions, let me know. Thanks!

For your phones that e-sims do work in, Airalo sells an e-sim that covers data. Works alongside your existing sim, and works UK and mainland Europe. There are other companies that offer similar service, but Airalo is the one I have used and worked for me. You get no traditional phone or text with it, but anything that works over wifi (WhatsApp/Signal/Telegram, Facetime, Skype, Google Maps, etc) all work fine.

As to a traditional sim, I'd look into a pay-as-you-go sim (even if its just data only) in the UK once you arrive. You can get these in grocery stores in the UK. Just take a look at some of the sims offered - for example, Tesco Mobile works in Europe provided you are in one of their HomeFromHome countries, which France and Italy both count as. (https://www.tescomobile.com/why-tesco-mobile/award-winning-network/home-from-home)

Tesco looks like it would be prefect for our trip! But when I look at their store locations, I don't see anything in the city center.

Is this one of the SIM cards that is available in grocery stores!?

Yes, you should be able to get a Tesco sim in stores.

Try this link: https://www.tesco.com/store-locator/

Use the postcode of your hotel to find the nearest to you. As an example, I used "Piccadilly Circus" as my search criteria and found this:

https://www.tesco.com/store-locator/?q=51.509903249999994%2C-0.13451125&qp=Piccadilly%20Circus%2C%20Piccadilly%2C%20London%2C%20England%20W1J%209HT%2C%20United%20Kingdom&l=en

Thanks! That shows more locations than my Google Maps search did. It was blocked, but I could access it using a VPN that ported me in to England.

Consider a SkyRoam portable hotspot. Can buy on their website or Amazon. Works in 130 countries and you can use on future trips. We just used in England, a Scotland, and Iceland and we were pleased.

Thanks to the poster who suggested the Tesco SIM card. It provides the same privileges in most (probably all?) E.U. counties as it does in the U.K.--unlike many other providers. I got this and it is working perfectly so far. The only issue was that I had to go to three different Tesco markets before I found one that had the SIM card in stock.

Just turned from London/Paris. Wife and I used Lyca Mobile sims that we picked up at Tesco that evening after checking into airbnb. 10 Pounds for 10Gb for London and Paris. You can only use 5Gb in Paris, but that was plenty for us. Twins (15 yrs.) have e-sims and I picked Airalo Regional 5Gb for $17, discount code son found. We activated the e-sims during our layover, before heading to London. We did use WhatApp for communication between us. No one complained.