Sim card use in UK and Europe?

Until brexit the UK is subject to EU regulations. When and if brexit occurs it may change, but for now roam like at home rules apply.

I can verify that Vodafone UK plans will work in many EU countries. Others here report 3 UK works too. Orange is a French telco so probably will be difficult to find in London. From what I’ve seen Orange plans tend to be more expensive than the UK providers and are only good for 2 weeks.

Be careful with GiffGaff - their SIMs may be great deals for the UK, but roaming in the EU may not be enabled until you have used it in the UK for a while first. I'd probably opt for the Vodafone UK SIM based on Rocket's and others' experiences.

Hi from Wisconsin,
I don't use my phone for anything but calls that must be made. I don't call home twice a day, or even once per trip. I use it when I have to. That said, MOBAL SIM has SIM card for $15 that will go into any phone that is unlocked and uses the European system (GSM). The card is good for at least a year and you get charged by the minute. I bought one and have used it for several trips. This SIM card works all over the world not just one nation.

Most other cards have two restrictions, Days and mInutes (gigabytes) .

wayne iNWI

I would recommend Mobal to people who have flip phones and/or just need to make calls, so wouldn't be using much data if any - because otherwise, if you use data, Mobal is pretty expensive. There are plenty of other SIMs for someone going to the UK and Belgium that will be a lot cheaper.

"I have a question about sim card purchase and use in UK and Europe."

It would be helpful to know what phone model you have and who your current network provider is. Are you need to make calls and where or is it primarily for Data? When do you plan to travel?
Also there is a "Technology Tips" forum under the Tips & Trip Reports.
Don
We use T-mobile with iphones and last year in London & Spain and we did not need to do anything had all the Data we needed for maps, texts and internet. Caution calling USA is expensive.

Thanks for all the responses. I have a Samsung Galaxy J3 2016 and I'm using Verizon. Since I posted this, I dropped the J3 and cracked the glass, so I'm going to buy a new phone and bring both on the trip. In the new phone I'll keep the US SIM card and keep it in my luggage. I'll put the Euro SIM in the J3 and use it during the day for GPS stuff. I don't plan to do any texting or calls unless I have a work emergency, then I'll use the US phone and do the $10/day plan.

That's exactly what I'm doing - old phone (with cracked glass) will have the Vodafone UK SIM; my newer phone, still with US SIM, I'll use in the hotel for WiFi calls and WhatsApp.