best SIM card in England

I have checked the shops and vending machines at heathrow. They offer a very limited selection of plans. I wait until I’m in town and go to one of the telco shops. I have used both Vodafone and EE and both have worked well for me.

https://ee.co.uk/mobile/pay-as-you-go-sim-only

https://www.vodafone.co.uk/mobile/best-sim-only-deals/pay-as-you-go-sim?icmp=uk~1consumer~topnav~1shop~2simonly~2payasyougo_sim&linkpos=topnav~1~1~2~2

Vodafone is usually less expensive. There’s also giffgaff which ships SIM cards overseas

Last trip I bought a giffgaff card online before I left home.

https://www.giffgaff.com/orders/affiliate/optim08922_1640028572839?gclid=Cj0KCQjw2qKmBhCfARIsAFy8buJC0xucGGBQCEIu4fXT5lf52xiH7D1Wx4eqqvataHfe6iRcdqUXnW4aAnIeEALw_wcB

It worked really well in England and Scotland.
Don’t buy one at the airport.
If it doesn’t work, then what?
If you’re not in a hurry on arrival day, just go to one of the hundreds of mobile phone stores near your first hotel.
Vodafone is always a good choice.

Seconding the suggestion of Giffgaff - I have a Giffgaff SIM that I use in the UK, and pricing is competitive. As noted, they will post it to you overseas so you can have it ready when you arrive.

Set up Google Voice on your phone before you leave the states. Then you can make free calls/texts to US phone numbers, even landlines, from the Google Voice app (needs WiFi or mobile data). Google gives you a US number too, so the person you are calling will see a US phone number in the caller ID, not a British phone number which might freak out some people not expecting it. And you can give people your Google number before you leave (and try it out) so they will have your Google number already in their contacts. Then when you call, it won't be a strange number to them.

I'm sure you will want the SIM card as well, but you don't have to use it to call the states.

Google Voice is good, but you can do something similar with Skype. I think you can purchase a phone number that lets others call you from the US, too.

There may be other services that do the same thing, too.

Having said that, I personally use Google Voice. I think it is a tiny bit more complicated to use than Skype, though, so it may not be for everyone.

And although purchasing a local SIM card is good for data and local calling, it may not be the best for calling the US. Using Google Voice or Skype over a data connection will likely give you much better per minute rate (and may in fact be free).

Alternative idea: Set up a Google Fi account before you go and use that account over there.

Another vote for Vodafone. I recently had 30gb for 15 GBP, which they almost immediately bumped to 60 gb. I use Messenger for calling North America and it works like a charm. Vodafone does not allow pictures to be sent via messaging people in the UK for some reason, but again Messenger came to the rescue, so I could send pics to my UK friends. Worth spending a few minutes in a Vodafone shop to get up and running properly by a person who knows what they are doing.

Paul:

Google Voice is good, but you can do something similar with Skype. I think you can purchase a phone number that lets others call you from the US, too.

Yes, you can do exactly the same thing with Skype (Microsoft). The main difference is that Google Voice allows free calls to all US phone numbers and Skype does not - you have to buy Skype credit and pay only a few cents per minute. Google gives you a free US number to receive calls on, Skype does not.

The OP did not even ask about this - I suggested Google Voice as unsolicited advice, I know. Since it's free to set up Google Voice, might as well try it - if it doesn't work out, nothing lost but a few minutes of time.