As the title says, it turns out around December many ISPs that use CityFibre such as giganet (https://www.giganet.uk/) (which is now cuckoo) https://www.cuckoo.co/ added DHCP support.
Previously it was required to use PPPoE which i'm sure everyone knows is antiquated and awful even with the new BSD driver. For me it would take about 40 seconds for PFSense to receive an IPv4 address and then up to 5 minutes to receive IPv6 which caused issues especially with IOT devices thinking the internet was down due to them connecting locally before PFSense had WAN access.
I highly recommend seeing if you can use DHCP. For me it was easy to set up under PFsense but i am sure other routers are similar.
Under the WAN interface, change IPv4 Configuration Type to DHCP and IPv6 Configuration Type to DHCP.
Scroll down to DHCP6 Client Configuration and leave everything unchecked except for Send IPv6 prefix hint. DHCPv6 Prefix Delegation size for me is 56.
The next step which is IMPORTANT is to navigate to System -> Routing -> WAN_DHCP -> edit (pencil button) -> Show Advanced -> enable Use non-local gateway.
This is all that is needed. Reboot pfsense and it should come back up with both IPv4 and IPv6 working via DHCP without the PPPoE overhead.
I'm sure its a placebo but sites seem to load much faster and i've lost about 2ms of latency it seems.
If you are able to move from PPPoE to DHCP, please comment what ISP you had success with. If you are unable to, please name and shame the ISP that still uses PPPoE below :)