Just had a look around, and found this.
http://www.serviceview.bt.com/list/public/current/Call_Charges_boo/0020_d0e5.htm...

"CHARGES FOR CALLERS TO THE 0870 NUMBER RANGE FROM 1st FEBRUARY 2008 - From the 1st February 2008, callers to 0870 numbers will be charged the equivalent of the national geographic rate (national rate calls to numbers starting 01 or 02). Details of these rates can be found at http://www.serviceview.bt.com/
Operative 19 Jan 2007"

Not sure if it means they'll be included in packages, or just 3p connection + 3p per min. Whichever would still be cheaper than current pricing.