Perhaps a member who is familiar with pfSense will assist, in due course.
For the configuration of the DrayTek Vigor 130, it should be left using the factory default settings. As for the configuration of your pfSense system, you certainly do not need to use anything ATM based.
A far as I am aware, TalkTalk do not use any credentials to authenticate a session which is provided over a VDSL2 circuit. Have you asked for advice within the TalkTalk "ecosystem"?
if you would like to experiment, configure your pfSense system to use a DHCP client on its WAN interface. If that fails, then try configuring the pfSense system to use PPPoE on its WAN interface with a null account name and account password.