Thanks for the comments, an extra £120 a year is quite a chunk just to watch HD content.
Andy@CRC, the offer they planned for us by calling them direct was:
£49 for the SkyHD+ box
£45 for the 1st months, (all Sky TV packages, HD subs free for the first month (£10)
Then I could drop it to £26.50 for the basic package if I wanted to after that.
Free Line rental for the first year (save £120)
Free Broadband 2meg
Free evening and weekends calls (sky talk freetime)
Free installation
£50 of M&S vouchers for both me and my Bro (via him recommending me)
(the other option offered was a free sky+ box each, but they would charge you an extra £10 pm for multiroom)