Thanks for the advice.
Although there shouldn't be any penalties to pay, my 12 months commitment ended long time ago, it makes sense to wait and see what sky has to say. By having a mobile with O2 I get an automatic £5 discount every month of my broadband, I'm pretty sure that will go with a move to Sky.
Reliability is very important to me so if Sky can provide that for me I would have to consider them come the time to make a decision.