i hope to soon be getting fibre here (see separate post)
i have a billion dxl router and want to ensure that it is giving me the best rates
don't suggest billion support, i have a mac which billion give no help for
The real question is which broadband provider are you going to be ordering through and which package.
Until such time as you know that, then worrying about modem/router is largely irrelevant, as for FTTP YOU MUST use the Openreach ONT. For FTTC you should use the supplied modem, but people do substitute their own and all in one routers are on the way from the providers in the Autumn.
I am looking forward to having Fibre broadband FTTC, when the Fibre VDSL router is self-installed by the customer, like it is now for ADSL2+ broadband. For my home it all comes from the same street cabinet. Soon the ISP will provide a Fibre VDSL router that the customer can install and no BT engineer required to visit your home.