All suppliers are required to treat 03 numbers the same as 01/02 numbers by Ofcom, and they must be included in your Inclusive Minutes.
"03 numbers
In 2007 Ofcom also introduced UK-wide 03 numbers as an alternative to chargeable 08 numbers, such as 0870.
These new numbers allow organisations to have a single national point of contact without consumers having to pay extra to call them.
Calls to 03 numbers cost no more than a national rate call to an 01 or 02 number and must count towards any inclusive minutes in the same way as 01 and 02 calls.These rules apply to calls from any type of line including mobile, BT, other fixed line or payphoneRevenue sharing - where the dialled party can receive a share of what the consumer pays to make a call - is also not allowed on calls to 03 numbers. "
http://consumers.ofcom.org.uk/news/telephone-numbering-3/Who is your current supplier ?