I have been using the Quantum X2D flash and its 400Ws output for my indoor studio UV-imaging. This gives me plenty of full-spectrum light which extends deep into the UV range. I had to build my system up from scratch, buying equipment from UK, Europe and USA.
I noticed a Quantum X2 flash as well as Quantum X-paq external battery (for use with the X2 flash head) in the UK for very reasonable price (under £270 for both items).
These have been listed at very reasonable prices, and if I did not already have my system, especially the Quantum Qpaq-X (which looks like it already has the extra module to allow for full 400Ws power), I would have bought this already.
But I thought I would post it here in case someone was looking for a powerful UV-capable flash system; just check with the seller that the Xenon tube looks clear i.e. uncoated, if using for UV-imaging.
BTW, one tip when using these flash with standard reflectors. It is worth cleaning the reflectors once in a while as you will be surprised at how much dirt comes off and it should improve the reflection of light (especially UV) to the subjects.