Sim Card - Vending machine or Tesco Express
 

I am only going to be in London for one day, getting in around 10:30 (er, 22:30) at night. I need a data only SIM so I can basically use GPS, Google Maps, Yelp, and maybe a little bit of browsing to find shops and such. So I want to pick up a Data SIM, that I may be able to reuse on my next visit.

At that hour most things are going to be closed. I know there are a few vending machine in LHR (I am coming into T3), and I did find a Tesco Express that is open 24 hours near Paddington. Which do you think I will have the best chance of finding a decent pay-s-you go SIM card (with Data)?

I will be going to London occasionally, so it will get used again. I tried the map thing in London (assuming you can even find one of those these days), and it was next to useless for me anyways, and I am a guy who LIKES maps! Yeah Yelp doesn't have a lot of support, though it has some. Google Maps is my main app of choice there. I used to have T-Mobile and they worked fine for me, but I switched to Cricket and now I need something for travels.

If you're only interested in using Google maps, then downloading the maps for Greater London on Google maps before arriving will be the cheapest method. The map won't include all features (e.g. Google maps will be incapable of proposing bus itineraries) but you'll be able to find any street, place of interest, closest tube station, etc.

There is at least one vending machine selling sim cards (there might even be two or three) in the arrivals hall of T3. There's a shop selling all kinds of sim but I believe that they are on the more expensive side of things. The vending machine has a couple of different packages from different operators. The vending machine is opposite the boots. Once you have left the secure area and join the public area, there's a ramp going down to the tube and the train station. The boots (& the vending machine) are to the right of that ramp if you're standing right in front of it.

Unless you travel to London frequently, chances are that any prepaid card will expire before you visit the UK again.

We will be in UK for about a week. Would vending machine be the most efficient way as well?

Thanks.

Yelp really is not relevant here. Google's own reviews are far more populated and useful, but they still require a connection even if you download Google Maps in advance.

For one day, I'd download Google Maps in advance and rely on hotel or coffee shop wifi for Google reviews and Citymapper directions (you should definitely get that app prior to arrival).

Other than that, SIM only is a much bigger thing here than in the USA so I'm sure that there are good deals around. Try Lebara or Virgin or any of the other MNVOs.

I echo use of Citymapper app.

But I'd check what your US provider would charge for data if you sort something out in advance rather than just use data roaming,

But if you are in London with plenty of free wifi around I'd question the need. I managed a week in New York picking up wifi in shops, starbucks, museums and the hotel without too much inconvenience.

You can buy a UK sim card from Amazon.com. It may be a bit more expensive than getting it in the UK. Might be worth the few extra dollars if you are pushed for time and just want to know you have it

Not every Tesco has SIM cards. But increasingly more of them do.. You pick up the SIM and if you present it to the human at the top-up counter and buy at least a 10 pound fill-up coupon, the SIM is free. After you install the SIM and download the credit you purchased, it is important that you then order a "rocket pack" or you will be charged for data at a crazy rate. To get a rocket pack, before making ANY call or using ANY data, call 282 from your phone. I learned this the hard way on my last trip.

Some SIMs automatically note that they are rocket pack SIMs but if it says on the SIM that it gives triple credit, it is not and you must call 282 right away while you still have the full 10 pound credit.

Rocket packs expire after 30 days.

Is this specific to Tesco mobile?

I would recommend Three PAYG which is 1p/MB and doesn't expire. Other providers may be cheaper for heavy users but this is the simplest. However the SIM is £1-£2 to buy at a shop and they may or may not be sold in Tesco too, and you have to buy vouchers to top up with non-UK cards, and it won't work in old phones that don't do 3G.

Free WiFi
 

It will be a Sunday so most banks will be closed. It will get used - I will give it to my brother who is headed over there in a few weeks, plus I am heading back in November. Which actually is another question - does Tesco work in Leeds?

I may just end up picking something up in the morning first thing.

Standing near to the bank branch usually works. What do you mean does Tesco work in Leeds? There are Tescos in Leeds and Tesco Mobile works all over the UK.

Tesco mobile piggybacks off the O2 network, so will work anywhere that has O2 coverage. I'm sure most branches of Tesco now sell SIM cards for all the main networks, as well as their own Tesco mobile service.

4 main networks in the UK - EE, Vodafone, O2 & Three (3), with various others selling services that piggyback off them. Unless you are going somewhere particularly remote, or are unlucky, any of the networks will provide decent connectivity.

Remote could be a little village outside of Halifax, but I guess O2 works there.

I ended up waiting until the morning and going to carphone warehouse. Got a 2gb data and phone sim from O2 for 10 pounds which was cheaper than internet. So that worked pretty well.