hid/gsi headlight conversion
depo lights (here) the seller has added £10 to the cost mine were £79 from this seller
other parts
GM-93171064 x2 D2S bulb holder
GM-91158536 x2 indicator bulb
pair of H7 bulbs for the main beam (i went with 50% brighter £14.99)
pair of push in side light bulbs
vauxhall corsa headlight plugs (scrap yard £5)
D2S hid kit with ballasts like (here)

i will post up the wiring config here as soon as i confirm the wires
wires on car to plugs
- side light : gray + gnd (brown)
- main beam :white + gnd (brown)
- dip beam :yellow + gnd (brown)
- indicator : black/white stripe + gnd (brown)
the new headlights have the following inputs (edit the common earth also feeds the indicator)

the after market ballasts have the same plug as the standard h7 fitting but with the polarity reversed you have to remove the pins from the plug and swap them over

heres my modified corsa plug with the extra wires removed
used 2 bent paper clips to get the wires out some were tricky and had to use some electronics tweezers
i have color matched the plug to wires for ease

just tested this on my spare psu all worked but the 55w high beam bulb shut the psu off lol