Certain you can cancel after the first 12 months, and in my area (Wales) they are promoting digital switchover deals (switchover dates from August through to March next year).
Granada has only two dates (04/11 and 02/12) and I'm actually on the edge of their area too.
The 'digital aerial' does sound to be a con! I know there are different aerial types (E is the wideband one) for areas with different groups of channels, but the max price I saw was 50 quid for the aerial - but ages since I've had any work done, so don't know what they'd charge for their time putting it up on a new pole.
As for Sky broadband (+ Sky Talk) - if you look on SamKnows.com you can check whether your exchange has Sky (see bottom right hand side and there is a list of firms, AOL, O2, TalkTalk, Tiscali, etc)... If Sky is listed there, then broadband can be had cheaply (tied to using Sky Talk too) but if not, then broadband is 17 quid a month.
Not sure whether you'd be locked in for a year with that 49 pounds + 30 pounds install deal. Here, because of the switchover, Sky is pushing the Sky+ or Sky+HD box for free, with a 50 quid Tesco voucher gift for the new customer, but taking a 30 quid installation fee and anything from 25.50 to 36.25 a month (17.50 for 1 Sky pack, plus either Sky Sports 1 or Sky Movies {9 or 8 pounds} + 9.75 for their HD pack).
Seen on another website (and I've also seen this in my local Asda, but it was below 75 pounds due to VAT reduction - I'm considering this option as it doesn't lock you in for long) :-
"Sky 'Pay Once, Watch Forever' deal from ASDA for just £75
Peter contacted us to say...
In my local ASDA in Llandudno, North Wales, I saw a package in a DVD case offering Sky free-to-air for £75. I decided to contact Sky and order the package. Everything went OK and they even gave me the choice of the 2 packages from them for the 6 months period so 'It did just what it says on the packet'.
The system is now installed and working.
According to the leaflet in the box the automatic mix is Variety and Knowledge but I was offered Style, Music, etc. The letter from Sky states 'Your Sky Pack gives you 6 months of top Sky TV. When the 6 months is up, you can choose whether or not to continue viewing all the entertainment Sky has to offer - we'll be in touch to find out'. It also says that the viewing card only needs to be in, and the phone line connected for 6 months."
The reason for needing the phone connection is to allow for a customer to use any premium services on top of whatever else they are watching. I know someone who has not had his box plugged in for years, but I think he's just been lucky - in theory they could charge whatever they consider the box to cost, if you break the terms set down in the small print, offering the box and installation for the (relatively low) one-off fee.
Clearly they want people to stay with them, having subsidised the cost of the box/install but as it's effectively a trial of the service, you just have to remember to cancel in time (perhaps a month before the end of the period).
Cancelling is described on another website, suggesting how best to go about it Online, by Post and by Phone (a 5p/min 0844 number). Mixed results on phone calls from 'straightforward' to 'very frustrating'. I think I'd do this Online.
If you go for Sky Multiroom they charge an extra fee for the second box to be using the service. As you are thinking of the Sky+ box, the LNB would have multiple outputs so you could feed a FreeSat box (or even FreeSat+) in another room if the LNB has 4 outputs. There's more info on the combinations on the web.
Now - my plan would be to get the Sky box and installation done, and later cancel it. I would like to get a big Plasma TV later on, so am thinking of FreeSat HD - boxes can be had for as little as 70 quid.
I have not looked very closely at the options for multi-room, because it would depend on whether the sat box also has UHF out (since that would easily feed other rooms with existing cables), but if they install a Quad LNB I'll be set up for all my needs, and can pick up a FreeSat PVR later on when they get cheaper.