I know no network has LTE yet. However its not just EE that will have LTE as Three have acquired an entire band (much like EE did) and will be offering LTE connectivity from that soon, obviously not in the next few weeks, but the rollout wont take too long. Given the very poor plans on offer from T-Mobile/Orange, you'll be hitting their limits pretty fast on LTE!
Even the Apple Store reps were recommending the Three plans. You'd be crazy to willingly pick one from O2 or Vodafone, thats for sure!
Basically to begin with only T-Mobile/Orange (under the name 'EverythingEverywhere') will offer LTE, with three to follow. No other network will have access to LTE, thus its a poor offering from them.