So it appears that we can add the BT Sport package to Sky, BT Sport 1 and 2 and ESPN for £12 a month + £15 activation fee, HD channels come free for a year, then it goes up to £15 a month to keep HD, channels launch August 1st.
If you have BT Broadband / Infinity it appears to be free.
Not for me I think, not prepared to pay more just to keep access to ESPN as I couldn't care less about the other sports they are offering.
Info Here