Ok so I've looked over the forum in relation HID conversion. I undersatnd that you can't do a swap into the headlamp as it makes the pattern illegal. But can you buy a full HID lamp kit including the headlights from anywhere?
Daniel Stern Lighting Consultancy and Supply
Hi there... I have been looking at upgrading the H7 dipped beam in my 156 as they are not very good at all!... hids4u (Google Them!) do a special kit for H7 (H7R on website IIRC) bulbs that are not going into a projector, but a reflector lamp. These DO give the correct beam pattern and prevents any glare to other drivers... although still not strictly legal... but the better you can see at night, the safer you are and as long as that is not at the expense of glare to oncoming cars there should be no issues really. The MOT will still get passed if the beam pattern and colour are correct.
Personally I think I will initially go for some Phillips Extreme Power (Auto Express tests them as the best) to start with and if they are not up to the bleak twisty North Yorkshire roads then I think that for £107, I will be going down the HID route!!