Sky's own installers won't do anything but a basic install the facilitate the package you've bought. At the moment the only option available from Sky is Sky Q. In general then that means a dish on the wall at no more than stepladder height, a twin cable from the dish and entering the house via the shortest route, and connected to a Q box. Any additional distribution is via Sky Multiview (the new name for Sky Multiroom), but the difference is that additional boxes work without direct satellite cable feeds. They use a network connection: wireless/wired Ethernet/powerline (but powerline is unofficially supported).
The sort of Sky system you're talking about is the previous generation Sky+HD system.
Sky's own installers no longer fit this. Independent contractors installing Sky as well as Freesat/Freeview may well do. Just check that Sky will (a) supply a viewing card and (b) activate it once the install is complete. They're really pushing hard to get everyone on Q. This only applies to new subscribers or people with a lapsed subscription. There are still some grey areas.
As long as you're confident that your system can be activated at the new address then here's what you can do to share the Sky system around the house.
I understand the desire to keep things looking neat, but I wouldn't recommend running the dish cables to the loft for a number of reasons. The main ones are:
1) House builders use crappy aerial cable. By crappy I mean the lowest grade, most cheaply made, poorest-shielded garbage it's possible to buy. It's barely acceptable to TV signals. Satellite signals need something altogether better because it runs at a much higher frequency where cable losses are far more acute
2) Trying to pull decent grade twin cable through the run occupied by the existing (crappy) single coax is an exercise in futility. That cable was installed during the build, and then it had insulation material added in the cavity. You've no idea whether the cable is pinned or inched at any point. You'll maybe get away pulling a short
run from the loft to a 1st floor bedroom without snags or damaging the cable, but to a ground floor room.... you've more chance of winning a tenner on the lottery
3) If/when your hand is forced by Sky to upgrade or switch to Q then all this work will have been for nothing. The Sky installers won't fit Q systems where the sat cable runs via a loft box
If you want to share the Sky box signal to other TVs in the house then your main options with a single box system are Sky's RF2 Out feature or distributing the HD signal via direct HDMI, or HDMI over Cat baluns/HDBaseT baluns, or HD via the house existing aerial distribution system.
Sky RF2 Out is simple, cheap and compatible with any TV that still has an analogue tuner. It also provides a way via the magic eye system to control the box. Aside from the analogue tuner requirement, the other prerequisites are
- an aerial coax cable direct to the box for Freeview in
- another coax cable (the return cable) from the box to the loft to carry the Sky RF2 signal mixed with Freeview
- a loft distribution box that's compatible with the Sky Eye power signal (referred to as IR Pass) if you want to run the magic eye system
- either a Sky+HD box with RF2 Out, or an I/O Port Adapter
Baluns/HDBaseT/HDMI direct all require additional cable being run.
The HD over Coax system is a viable alternative with minimal impact during installation and makes best use of the existing aerial distribution network. It is compatible with Sky Eyes and can even accommodate Sky RF2 + HD. The secondary TVs need to have an MPEG4 tuner if you want to watch in HD; this is the tuner type required to receive Freeview HD, but that's not a requirement if using a combined HD + RF2 Out over coax solution.
