Thought I'd post this on here as it may prove useful to others at some point. I snapped the connector to the headlamp washer pump on my facelift ZT when removing the hose to diagnose a fault with the non-return valve.
X-Part only supply the complete hose assembly (DNH000250) and these are £71.63 +VAT from the only supplier I could find (A E Wilcox).
However, I have found that these are made by Hella and are used on various other vehicles. The non-return valve is available from BMW for £9.11 +VAT on part number 61668361447.
And the pump/washer connectors (these are a 90° fitment, two on the original hose are 70° or so, but these are very similar and fit OK) are also available from BMW on part number 61678252741 for £2.00 each +VAT.
Hopefully this helps someone someday!