I have a Sky+ HD box in my front room and had multiroom but removed it from my bedroom.
The Sky engineer said that I could get a 'Magic Eye' that would enable me to watch and change channel using my box downstairs from my bedroom without the need for a Sky box in my bedroom.
I had one before I got multiroom put in. A little mouse type thing sits on top of the telly and you point the Sky remote at it to control the box in another room. It needs setting up properly which I can't help you with (I'm sure someone will be along later who may know). It worked a treat.
You need a LOFTBOX generally in the loft but not always.A coax lead from the sat box in the front room..this is the UPLINK.Then a coax from the loftbox to each tv.The magic eye receiver is powered via the coax connection into each additional tv and is instructed with the additional sky handset..
So you need
Loftbox
uplink
downlink per tv
magic eye per tv
Quality sky remote per tv (or move it from room to room)
Note the same channel will be shown in each room...if this does,nt suit then its back to multiroom and additional subscription.
BRIGHT SPARK's solution works well but won't give HD video or stereo audio.
You can get a Digisender that does give HD and stereo but suffers from interference in many environments, making it usable only as a Remote Control sender rather than an audio/video sender.
As an cheap, simple, quick alternative if you have a tablet, consider Sky Go: