I have opted to cancel my land line and have been offered this service, will I be charged for this, ie like the landline there was a landline fee.
There is no 'landline' fee, there used to be a separate charge of line rental which is nothing to do with telephony but that has now been subsumed into the broadband package price.
Call charges are exactly the same for DV as analogue.
If you have ‘landline’ and ‘broadband’ , then you pay one fee for the service, there is no subdivision of £x for landline and £y for broadband, to give you a bill of £z, you simply pay £z for both , if you want to remove the option of having any associated telephony , that can save some money.
If you have been offered DV Digital Voice , apart from the technology the telephony is delivered over , nothing changes , so there will be no ‘saving’ , you will still have telephony ,
If you asked said to remove the ‘landline’ and by this you mean , remove all telephony completely , so no incoming or outgoing calls , including 999 calls are possible, you would not even have a phone number , then it will not come with DV , if you are getting DV the only thing that changes is the phone plugs into the router and there will be no saving for not having telephony, because you still have telephony.