Cdc's can charge what they feel is appropriate, and some do charge an initial consultation fee etc.
The £46 per week is the average charge for somebody who has to have 4 packs a day.
If you're not happy with the cost you could ring round and try to find another counsellor, there are many who only charge for products, but I think the only money you will save will be on the initial consultation fee. To be honest if this counsellor has a good reputation I would stick with her. There are many who may be cheaper but don't offer the appropriate service.
Good luck with the diet.
Tracey
x