i am on Halo 1 broadband at the moment paying £61-12 a month for 150mb, i see on BT deals i can get Full Fibre 900 without my landline ( i never use it ) for £54-95. when contacting BT I'm told i can only have Halo 3 at a more expensive monthly payment, i only live in a small house so not interested in the so called benefits of Halo. my contract is up on 8th of Jan 2022 so they told me to enquire then as they cant make anymore offers , not a very helpful suggestion from BT after being with them for 3 years,
my home is fibre fitted and i can get the 900mb speed
you still have to pay line rental whether it is a fibre connection or copper otherwise you cannot receive broadband without landline is just you no longer have the facility to make or receive calls on landline but unlikely to reduce cost unless you currently have a calls package which you would drop
As you are in a fixed contract for a fixed length of time at a fixed price, the best time to upgrade /change would be at end (or just before) of contract.
the reduction is due to a call package which you are dropping