EE is by far the best network in the UK. I don't even look at what's in store with their competitors when picking up a SIM for my visits.

Their offer can be a bit tricky to navigate though. I found that you can get a phone SIM with a data pack for 15 quid, netting you 4GB of data (plus calls and messages) or a data SIM at the same price... with just 2GB.

I used 3 Mobile UK when I was there and even got to use the data allowance while in France with the "Feel At Home" feature.

And also learn how to use Offline Google Maps - it worked on my spare iPhone which has no SIM but because of inbuilt GPS it still worked with the downloaded maps.

and don't forget the Citymapper App - very useful when I was in London and Paris. better than Google Maps for public transport IMO.

Just spent a week in the UK and I must say I wasn't that happy with my mobile internet connection this time around. Maybe it sounds like blasphemy (yikes! ), but I think Telstra are doing a fine job in AU compared to the number of problematic areas I've encountered in the UK.

UK infrastructure overall, both digital and traditional, seems to be behind the times compared to many, many parts of continental Europe.