I always phone up BT when our contract is almost up, I find I get a better overall deal and it has always paid off doing so.
You might be lucky and have that deal you made over the phone auto start at that point or when your current contract runs out, but remember to confirm what you agreed to before you get off the phone, a few times they got it wrong, so getting them to confirm the deal you both agreed on helps.
Also don't forget that £42.99 you pay also includes your line rental so you are paying about £23 to £25 per month for just your broadband.
I won't say exactly what we pay for the broadband but its not that much more than what you pay, but I had to work hard to get our current price.
Also enquire when phoning BT once FTTP is available to you if you can pick a lower speed package and possibly upgrade a bit later if that speed isn't enough, they might allow it, I know a neighbour of mine did that and BT was fine wit it, but I think you are allowed to do this a certain amount of times a year, so you might need to ask about it.
That way you are not paying for speeds that you may not require.
We picked the 330:50 (Ultrafast 2 Plus) due to I am more interested with the up speed, if they did the 200:100 or 100:100 I would of gone with one of those.
Like at the moment if I create video content with a file size of 20GB which some have been it would take me with our current up speed of 50Mbps around an hour to upload to YouTube or Twitch.
But the current price we pay I think is rather good and worth it and would renew at that price at a heart beat.
Paul