You may already have a BT Business Hub. The BT engineer will bring a Fibre modem with them on installation day.
Let the BT engineer setup the new connect.
Once they’ve finished plus the BT Fibre Modem into the ethernet WAN port of the Draytek (in my case a 2820). Configured the draytek to enable the ethernet WAN and configure it with PPPoE authentication. You must but in your internet username and password as well if not you get a private 172.16.x.x address. In my case the username and password were exactly the same as the ones I’d been using for ADSL. Your IP address (assuming its static) will be exactly the same as well.