What's the outer diameter where it inputs into the end of the heating element tube?
I ask, as I'm wondering if Quick's NK series nozzles will fit (I don't have a proper caliper, but I'm measuring 22.5mm on mine using a stainless steel engineering ruler). They're rather well made actually, and not terribly expensive either (no where near what Metcal's nozzles sell for).
NK Series Nozzle Datasheet (.pdf).
Somerset Solder &
AMS both sell Quick in the UK, so they should be able to get them for you (also look for the 861DS; usually the sellers I've seen in the past were located in Poland). Maybe even eBay, if you can get them shipped from a US seller.
FWIW, I've been able to solder/desolder anything I've come across just using the 3 round nozzles that were included. You can buy or make shields to protect nearby components if need be (
JBC shields).
Basically, they
borrowed from Weller's nozzle design methodology, but offer them at a fraction of Weller's prices.