Even then, the IPv4 address is dynamic. I don't know how BT handle IPv6. With luck that is static, but finding out what it is could be tricky.
Kindness isn't going to cure the world of all its awfulness but it's a good place to begin. Daisy Ridley.
My broadband basic info/help site - www.robertos.me.uk.
Domains, site and mail hosting - Tsohost
Connection - AAISP Home::1 80/20. Sync 54999/14466Kbps @ 600m. BQMs - IPv4