As Tomsk mentioned, I just got an email from GiffGaff and their £12 plan (previously unlimited data) is changing to 3GB, 500 minutes, unlimited texts. Useless for me as I honestly don't even call or text that much anymore. I've always felt their data speeds are very hit and miss too, so I'm long overdue for a change in network.
I was looking at EE and 3 to see what they had as data is most important to me, and I'm shocked to see that EE is so expensive. Even just 2GB of data still costs £20 on a 12 month contract. Month-to-month then it's £23. So I think it's 3's £15 unlimited data plan for me, which is great as it's the same price whether you go for month-to-month or a 12 month contract.
Quick question about the 3 £15 1 month SIM though - once I've activated it, can I then log into my account and have it automatically rebill me every month until I choose to stop it? So for example I could activate it on Sep 01, and then 8 months later during the middle of the month I could decide I want to stop and simply deactivate automatic payment?