This started in Oct 2012 (I think), and I've been doing it since then! A long runner but hasn't been posted for a while. Just sign up for their card, either scan yourself on self-scan or at the till, get given a cup, and go and fill it. Many branches now have "bar stool" type arrangements, such as the 2 in Manchester centre and Croydon. Some big stores like Westfield Stratford City in London, have actual tables and chairs for free coffee customers to use. The coffee isn't amazing but is OK. Real milk for tea, not UHT, is a big advantage over some cheaper coffee options. Some branches have it in a stainless steel flask, others a button on the machine for "cold milk portion".