I've renewed my 1gbps connection for another 24 months, didn't mind about the CGNAT issue given I'm not really using any services that would be hindered by it at this time (and my Synology when upgraded will likely be using Tailscale or some such to get by for external access when I finally get the upgrade). Was given 1 month free so only paying 23 months at £26 + £10 for the landline (as we need it for medical calls to and from GP and Hospitals for my mother). Didn't get through to a tech team to ask about why the change to CGNAT mid contract last time but felt it wasn't a big enough issue after working out the route for the new NAS later down the line.
:: edit ::
Strangely, looking at my router right now, it looks like I've been taken off of CGNAT. Really weird. Will keep an eye on it and see what happens. I did prior to renewing send a query to their online teams about it before they replied back to me and told me to call them up instead. So I wonder if this is them giving me back a public IP or if it's temporary only? Time will tell I guess. But certainly nice as I can make use of it if it remains.