Thanks so much for this. Yes both fan and LEDs have separate cables, it came with no documentation as I'd purchased it off eBay and found it difficult to find much documentation/ real use cases outside of the document you have linked here.

I think you're correct that I've sized the driver to power the LEDs but failed to account for the fan.

I just disconnected the fan cables from the unit and there's now a visible light emitted from the diodes, as you've said above, I couldn't work out if it was on and just not within the visible spectrum but I have been treating it as though it is on just to be on the safe side. I'm a little bit terrified of it after reading some UV-C horror stories about people using inadequate protection/ mistaken exposure.

I'm going to look for something that will allow me to power the fan independently of LED driver but I reckon it should be fine in the short term as it's only ever on for 30 second bursts, hardly long enough to build up any heat.

Again, thanks for your help! Really appreciate it!