on 23-05-2021 08:35 PM
If you have asked your new supplier to switch your service from TalkTalk and keep your existing number then they should notify TalkTalk directly on your behalf. Otherwise, or if you are switching to a Fibre provider such as Virgin Media then you will need to cancel yourself.
on 23-05-2021 11:56 AM
How do you mean "gap?" From when the contract ends?
Generally speaking you will continue to be billed in advance on your usual monthly date up to the date of the switch. If any discounts expire you will be charged at standard rates on a pro-rata basis. Once the switch has completed your bill after that will show any balance outstanding, or credits due to you. This is all assuming you have asked your new supplier to take on your existing number.