We're using EE PAYG, but don't tend to use the phone much. It's 5 pounds a month for 50 minutes of phone, 250 texts, and 150meg of data (which we don't use). If you buy this "pack" from them for three months, they give you bonus minutes or texts at the end of that three months' time. I think that we only had to purchase extra minutes the first month that we were in the UK, as we were having to spend time getting housing and then utilities set up, and now the phone is just back to being a "carry it when you go out for emergencies."
They do have other PAYG plans with more minutes, etc. and we've had absolutely no problem with reception.