Noraml HDIP courese, unless they are a teaching related qualifictaion, are not allowed onBTEA and its a complcated area. contact your Local Office with exact details of the coirse and they chouls be able to tell you if it qualifys.
I don't think the OP means HDip in the postgraduate sense. If it is level 7 as you say and in a recognised third level institution then the course would be eligible for BTEA - provided you meet the other criteria for BTEA.