Switching, but...

I want to avoid 21CN if possible. Cable is not available. What options do I have, if any? If I find an LLU provider, does this circumnavigate 21CN?

Yes, using LLU means you won't be using BT's 21CN. Which exchange? See http://www.samknows.com/broadband/exchange_search

If LLU it avoids it for the DSL, only a fully umbundled line will avoid it for phone too

Thank you for the replies.

I have O2 and Sky as viable LLU options. Will I automatically be on LLU if my exchange is enabled? Or do I have to specify this with customer services?

With both O2 and Sky they should put you on LLU but they do both do a BT wholesale version for unbundled or full exchanges. With O2 avoid "O2 Access" and with Sky avoid "Sky Connect". By default though with an unbundled exchange you would get their LLU product.

At the O2 site start applying for BB. If it offers you the 3 LLU packages (O2 Standard etc.) you're OK. If it only offers you O2 Access, then LLU is full and you shouldn't buy.

As the others have said, but up till the end of this month there is also £45/£50 cashback available from O2 if you clear cookies and sign up online through Quidco or TopCashBack. Of the two I reckon on Quidco, who take the first £5 you earn each year.

See MKD's O2/Be comparison documents for useful information and particularly the costs.

However also be aware that Sky Unlimited LLU is (in my opinion) nearly as good as O2 and you no longer have to have Sky TV.