Grab a free EE PAYG SIM and top it up with £5, and you'll get 100MB of 4G data free. Every month. For life. EE says that’s roughly 2,000 Whatsapp messages, four hours browsing, 200 social media updates, 20 downloaded tracks, or 2-3 game downloads (depending on size, obviously). Better than a kick in the privates.
Full terms and timescales and whatnot right here.
(Thanks to billbennett1 at HUKD)