O2 is joining the 4G LTE war on August 29, and they've now released their the package pricing. They will start at £26 a month on SIM-only, that will get you 1GB of data, if you pay £36 a month you'll get 5GB of data. If you want anymore you'll have to pay £6 per month more for 500MB and £10 for 1GB. Until October 31 O2 will offer extra data on top of the set amount for the duration of the contract, likely an incentive to drive customers over to 4G.
O2 expects to reach 98 percent of the UK by the end of 2015 but unfortunately it will initially be slower than EE's network, plus it won't work with Apple's iPhone 5 at all. Telefonica UK CEO Ronan Dunne said he “would be frankly gobsmacked if [Apple's] roadmap didn’t address that issue.”
UK network Vodafone is also planning to launch 4G on August 29 which will come with a Spotify Premium account or Sky Sports Mobile as part of your plan.