Interesting things emerging in this thread. Having never even had an LLU option, it hadn't dawned on me that some IPSs may be slower than others to offer an FTTC service, even after the exchange and cabinet are enabled. My exchange is not yet enabled, so I don't think I have any way to predict initial choice of ISPs?
My plan remains, to transfer existing ADSL to Zen. If they are able to offer Fibre at my address when the if/when the exchange & cab' are ready, then all well and good. Otherwise, I guess, I can switch again as it's a one month contract.
Zen are probably not the cheapest, and the 50GB limit on the FTTC basic package could get swallowed up very quickly with Fibre, leading me to upgrade soon after. But I'm pinning my hopes on their reputation for service & support living up to promise - that makes up for so much!