Doesn’t really exist, its still same old copper wire up to your house. However BT are replacing the copper wire from the exchange to the PCP (green box round the corner) with fibre optic drastically reducing the length of the copper wiring to your house. This improves the Maximum speed of the broad band alowing faster contracts. BT market this as BT infinity, i have seen this working at 65Mb/s .
Fiber all the way into the property is available but its only for big bussines's with deep pockets.