Leaving Plusnet for Sky - MAC code?

[#1]

I am moving house in to a new build and have been offered a good deal by Sky on combined TV, broadband and phone. I am leaving Plusnet reluctantly as I have had excellent service in the long time (8-9 years?) I have been with them. I have arranged for Sky to come on 20th May to install a new phone line and broadband. I tried to ring Plusnet cancellations department earlier but they had closed for the weekend.
I see posts where people are talking about needing a MAC code to move their service to a new supplier. Please can someone tell me what this is and whether I need one. Many thanks.

[#2]

MAC = Migration Authorisation Code
This is used to give your new ISP authorisation to migrate the broadband service on your phone line to them. In your case you have a new phone line so it does not apply. You have to cancel your broadband service with PlusNet for which BT will charge a cessation fee.

[#3]

Thanks, Peter. I will be cancelling on Monday.