After a bit of back and forth with the BT executive office, they got OpenReach to come out on the Saturday just gone to install the line. Have to give them some credit as you can't actually book a Saturday appointment, but I really couldn't take more time off work as my holiday year runs August > July.
Getting ~520 down / ~75 up on the 500 package. Just got to wait for my electrician to come out this week to install another Ethernet socket and change the face plate on another one to dual port, the OpenReach engineer was obliging and installed both the CSP and ONT internally into the garage (attached to my bungalow) so I'm currently running an odd layout mesh network without a backbone. My old connection came directly into the lounge, with an Ethernet cable running from a socket there, into the loft, and down into another room (Modem > Router > Ethernet backbone to another Router layout for great WiFi coverage).
BT owe me automatic compensation as well, so I guess my account is going to be in credit for a while. Pretty happy with the outcome.