It would be faster for BT to upgrade a exchange for FTTC first and then do the FTTP install, as the largest customer base has been enabled and can take orders while the longer FTTP installs can then be done.
Cost is the main factor in the rollout, why alot of FTTP has been dropped in favour of FTTC. If you look on BT openreach site 'where and when' the fttp list is for new builds mainly, where it is cheaper to install during construction.
Their will be a certain % of FTTP in the end of the rollout, just a heavy majority towards FTTC.
Having FTTP on demand also can remove alot of the need for BT to deploy FTTP out of their own funds.
As for Sky offering FTTP, will have to wait and see if they decide to once their FTTC product has launched.