If your cabinet was not getting fibre, would you stay with BT or move to Zen here and now?
If you would move now then do it now. Fibre enablement dates are highly changeable and the upgrade can be delayed many times or even fall through.
If you are only contemplating moving to Zen for fibre, and moving now would just be to simplify the process in some way, then stay where you are. For the above reasons.
There is no reason in the Openreach and BT Wholesale systems why you couldn't move from ADSL2+ with BT to Fibre with Zen. Whether Zen have the systems in place to do it I have no idea. I would ask them, unless a later poster knows.
Kindness isn't going to cure the world of all its awfulness but it's a good place to begin. Daisy Ridley.
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