I'm wanting to move to full fibre, currently I have the phone line by the front door, this is then extended (hardwired) to up stairs where my Router sits. The fibre box will replace this am I able to extended this to the same place via a fibre extension cable.
The 'fibre box' (ONT) doesn't necessarily have to be where your current master socket is sited. The output from the ONT to the router is Ethernet, not fibre so just run a Cat5E or better Ethernet cable from the ONT to the router.
Discuss where you want the ONT sited with the installer when he comes, there's no guarantee you'll get what you want but they're usually pretty flexible
That's simple enough, I have Cat 5 running everywhere ATM so one more shouldn't make a difference. I want to get prepared before I make the switch.
Cat 5 isn't good enough , it must be cat 5E or above.
Personally I use cat 5E as it's more flexible that cat 6,7 or 8.
Are you aware that you will need a 13A socket available to power the ONT? This may have a bearing on where you decide to have it located.