In the UK, only one big(-ish) ISP supports IPv6, and 2 significantly smaller ones. BT claim to be pushing it out next year, but they still have a large number of older consumer-end router/modem devices which can't be updated for it, so it'll take another half a decade for those devices to fail and be replaced. Once BT have pushed it out, many of the companies that depend on them for varying things should be able to build implementations fairly quickly.