When you take out a VPN + BT Infinity, all websites will be available. Remember, BT can only compare with SKY, when you add VPN. Without VPN, BT Infinity is worthless - I would rather use a 4MBit connection that BTInfinity.
I tried to use the cashback service yesterday, however, it would not allow me to order online. I then went to sky forums and apparently, you can only order Fibre broadband, on the website, if you are an existing sky customer. I'm not sure how true this is.
On a further note, I spoke with my existing BB supplier and apparently, SKY are scheduled to take over my phone line 2 days before they fix my BB connection. This means no internet for 2 days. I've been on the phone with SKY for 30 minutes to try and get the full changeover to happen on the same day and they say that they do not have the expertise to do this and that I need to call back tomorrow.
If this continues, I may have to cancel the order and go with BT + VPN.
Because I work from home and cannot afford to have any **** ups and given my experience so far, it would be a miracle if SKY manage to take over my line without issue.