Well I tried posting on the Sky support forum and again was told the same thing about my number coming up as non-transferable.
So I called Sky's broadband team expecting to hear the same thing and the bloke on there didn't even flinch when I said I'd have to keep my number... No problem at all apparently, I might get a bit of a delay because of the process but that's all. How 5 difference Sky reps can all come up with the same nonsense is beyond me, its like they all read the previous reply to me and just backed up their fellow employee.
Anyway I'm finally being moved, and as an apology of sorts he's given me Sky Movies free for 3 months and my talk package free for 3 months.
Regarding LLU, I don't think its really a problem, it just comes down to clueless people not wanting to do a thing for a customer. I've actually had pretty much nothing but good service on TalkTalk LLU and of course the price difference in comparison to what I was paying before is quite significant.
I just hope I don't regret leaving TalkTalk, like I said I've had no problems with their service and actually had excellent customer service too (via the support forum). I just like the sound of Sky's unlimited service and Sky Anytime+. If I went anywhere from Sky it would probably be back to TalkTalk if possible