When to cancel contract?

[Tony94]

My contract is due to end on 17/06/2021 and final bill is due on the 01/06/2021.
I wish to keep my number and move to a different network, after reading many things saying I need to give 30 days notice but will also be charged a termination fee, when can I cancel the contract which would be fully paid off on the 1st, without being charged extra?

Its my understanding that I would be out of contract and therefore no need to pay a cancellation fee? However will I be charged a fee if I "cancel" on the date my contract ends, even though the bill would be paid fully 16 days earlier?

[MI5 · Accepted solution]

@Tony94 

All explained here Guide: Cancelling Your Contract