Self-install - Master socket question

[#1]

Hello,
I'd really appreciate some advice!
I am currently on ADSL with Plusnet but am considering switching to their fibre but am a little confused about the installation process.
I understand the standard model is that OpenReach will visit your home, change the faceplate on the master socket and connect up the modem (provided by BT) and the router (provided by Plusnet) to the master socket. Alternatively an extension cable can be run from the master socket and the modem and router plugged in wherever this terminates. Other telephone sockets around the house cannot be used to attach the modem/router.
This isn't really going to work for me as my master socket is in an unusually difficult location - no power nearby and running an extension cable from the master would be no mean feat either.
Reading between the lines I am wondering if a self-install solves this problem (if Plusnet do them). Am I right in saying in this scenario an OpenReach engineer doesn't come to the home and that filters instead are put onto the existing extensions so that the modem and router can operate from any socket (ie. not just the master)? I understand this may reduce speeds but to be honest I'd be fine with that if it meant I could keep the modem/router where it is now for my ADSL connection.
Thanks in advance for any advice folks can give.

[#2]

I'm in a broadly similar position to you with respect to the master socket position. However, my ADSL setup had two CW1308  "extensions": one filtered for phones and the other (about 6m) unfiltered to the ADSL modem.
The switch to fibre (by a contractor) was done by fitting the new filter plate, a new phone extension removable plate (instead of the old filter plate) and reconnecting the two cables, followed by transferring the modem patch lead to the ECI modem.
I have a reasonably short connection to the cabinet, so my current modem/router (TPL W9980) syncs at 79997/19999Mbps.
If your current set-up is unfiltered extensions with plug-in filters at each socket and the cable is not the old "4 colour" type, that should work unchanged, but sub-optimally, but you should ensure only connection 2 & 5 are connected (ie no ring wire link).
If you have 2-pair (or more) cw1308 for your extensions, it may be possible to use one pair for the phones (filtered) and one pair for the modem (unfiltered) to the first extension socket, but you will need a plate with two sockets, one for phone and one (RJ45/ethernet usually) for the modem.
Phil

[#3]

I believe you can request a data extension when placing the order.  This will put a new filtered socket somewhere else in the house where you have power. 
From the PN FAQs:
What if I can't or don't want to use the master socket?
If your master socket isn't in a handy place (e.g. if there are no nearby power points, or it's in a garage or attic), the engineer can fit a data extension cable. This will let you install the fibre modem up to 30 metres away from your master socket. If you're thinking about this, try to pick the new location before the engineer arrives.
https://www.plus.net/home-broadband/faqs/fibre-optic-broadband/