I'm going to order these, as the price is such a bargain compared to a few years ago and - err - compared to the RIPOFF prices of the products available in NZ, where it's almost impossible to find HB3 kits anyway.
I don't live in England but I think the whole MOT issue will continue to be a matter of common sense. By the letter of the law they are not legal simply because they are a retrofit into halogen-approved headlights and that is not allowed (regardless of washers/beam levelling: "if those devices are fitted they must work" is the principle there, not "those devices must be fitted" - subtle difference).
The common-sense part is that not all headlights are created equal. Reflector optics rely on the position of the bulb (and size of the filament) to set the focus and shape of the beam pattern. Projector optics - which the GTV has - rely on a mask to set the shape of the beam (and a lens that focuses on that mask) - the position of the bulb is still a little important, but the mask really helps to block out any stray light.
All European OEM HID lights that I have seen use projector optics and when you take them apart, they look very similar to the headlights fitted to the GTV/Spider. Some older Japanese and American OEM HID lights use reflector optics, and you probably won't see them on the roads because they don't meet European standards. Of course, we have them on the roads here, and they're a nuisance, but they pass the test because they're OEM!
Therefore if the beam pattern is correct without scatter and the colour of the light is 'white' (not blue), then it will probably pass, and if not, well, it's an easy swap back. That's how it goes in NZ anyway.
Put in cool blue 8000K or 9000K HIDs and you're just asking for trouble, IMHO. That's an easy reason to fail, as another rule says that the light must appear 'white'.
Putting HIDs, particularly the older kits, into reflector-optics headlights - and many new halogen-bulb designs on cheaper cars are still reflector optics, like on my FIAT 500 for example - will probably create a blurred and scattered beam pattern and another easy fail.
As for colour, the original manufacturers use 4300K for a reason - it works best - roadsigns and road verges are not blue, so you don't want blue lights. "Simples" as you guys say!