Hub One/master socket set up

[#1]

Does the Hub One HAVE to be connected to the master socket? My master socket is in our hall with no power supply nearby.
I have been with Plusnet for years and currently run an ADSL set up. I want to change to fibre, I know that it is available on the lane where I live.
I currently have my ADSL router next to my PC upstairs (about 15 yards away from the master socket). It is plugged into a phone line extension socket. That is where I would like to have the Hub One unit.
I have 2 other phone extensions with splitters attached and the wifi is boosted downstairs using a TP link for our tablets/laptops etc. We achieve 5 mbps.
My master socket is called an Openreach Linebox, which was an upgrade fitted by BT in early 2015, shown here on Amazon: http://www.amazon.co.uk/GENUINE-BT-OpenReach-Linebox-Connection/dp/B007ZH2PFY
I would like to know if I am all set up for fibre if, once I receive the new unit, I connect the replacement router/modem Hub One where my current router is?
Any help would be appreciated thanks.

[#2]

Recommendation is to connect the 'Hub One' to the master socket but will work when connected to a secondary outlet. Possibility of a slightly slower sync / transfer speed.

[#3]

Does the extension cable from the master socket to your current modem have any other extensions spurred off from it?
Also, do you need to have a working phone socket in the same room as the modem?
If the answer to both these questions is no, I would replace your master socket with a MK3 master socket and connect the modem extension to the AB (unfiltered) terminals on the new master socket. I would connect the other 2 extensions into the filtered terminals of the master socket.
This would mean that the only extension carrying VDSL signals is the one to your modem. The other extensions would be filtered and for telephone only connections, so you wouldn't need separate microfilters for these anymore.
The advantage of this setup is that you are filtering right at the master socket instead of at the end of each extension cable, so there should potentially be less losses.
If you really wanted a phone at the location of the modem, you could still potentially use a microfilter there.
If the answer to either of the first 2 questions is yes, you can simply keep the same setup, using microfilters.
The short answer to your question is that the Hub One does not need to be connected directly to the master socket. Because VDSL2 signals (fibre), use higher frequencies than ADSL (or ADSL2), there can be more losses over extension wiring. So it is preferable to minimise the amount of extension wiring you have to use. That is not to say it won't work, it may just not be optimal. Many people that want extension wiring for fibre use a good quality twisted pair cable for the VDSL2 extension (e.g. CAT5 cable). The worst cable for VDSL2 extension wiring is usually the flat cable, as it is not twisted.
However, every installation is different and I would say try the existing setup and see what speeds you get. You can compare speeds by connecting straight into the master socket as a test.
A lot of info but if you need more clarification, just ask. Also, there are plenty of people on this forum that are quite expert on this stuff who can also advise.

[#4]

Yes we do have an extension spur off the master socket, and yes (sorry :-[) we do really need the phone near the PC and the modem.
The cable is flat throughout the house unfortunately as well.
A couple of follow up questions:
1. Is it likely that we would lose a lot of speed with our current set up? At the moment we only achieve 5 mbps with ADSL and a BT engineer recently measured fibre speed at the socket to be the full 38 mbps (the BT cabinet is at the bottom of the lane, about 150 yards from the house, so is nearby). If we achieved 20 mbps we would be eternally grateful TBH!
2. Would upgrading the master socket to a mark 3 faceplate help at all?

[#5]

It is hard to say how much speed you would lose.
Upgrading to a MK3 faceplate would help if it would prevent the VDSL2 signal from going to every extension you have. For that, you would tie the telephone only extension wiring into the filtered connections and keep the extension wiring for your modem on the unfiltered connection.
If the cabinet is nearby, none of this may be an issue so your best bet would be to just go for fibre (if thats what you want), and see what speeds you get. If you do find that you have a problem with speeds, then you can look at some of the measures to help - you may not need them

[#6]

Thanks for your time and help. I will do as you suggest and go ahead with upgrading to fibre and see how we go with it.