There will certainly be black friday deals out there. Whether any of them meet your specific requirements I wouldn't know as not all packages and not all ISPs will have discounts. It's a gamble as to whether you temporarily pay a likely higher rate from the end of your contract until you can see the black friday deals or whether you take the plunge and take whatever good deal you can get before hand. It's also possible if you are waiting for Sky to do good deals that they might only offer black friday deals to new customers (I don't know if this is how Sky do it).
It will be just over a month from end of contract to black friday but you also need to factor it will take likely 10 days to do the switch. So, you have 6-7 weeks I would say where you will probably be paying a higher rate with Sky.
It's a gamble. Only you can decide whether the gamble is worth it. If you do decide to get a new contract before black friday then I would suggest not looking at the ISP black friday deals as you will only get annoyed