Re: Worst Coverage?
Very similar for me too, I live near Glasgow and work on the other side of Glasgow at the moment but also with a fair bit of travelling. I get pretty good coverage almost everywhere with 3. Previously I had a business phone from O2 and the coverage was not as good, nor was the customer service. As much as comparing customer service from mobile providers is like comparing having rabies to botulism, 3 are about the best IME (Been with Vodafone and Orange around the time it became EE before moving to 3).
Never dealt with TalkTalk for anything other than business broadband and their service is, in a word, shite. Everytime I called them it was either my fault for not using their router, or Openreach's fault.