You don't have to take the bumper off! I didn't and saved myself a heap of time, took about 5-10 mins, bumper off job takes about half an hour or more!
Take the fuse box off, this will give you a bit more room and will leave you with the rubber surrounding. Twist and pull the Xenon box away from the light and un plug it. When the box is out you can then take the light out.
To re fit you can put the light into the box or reverse the above method. Both are tricky however as you need space. I put the bump into the Xenon box and pushed the box up to the rubber around the fuse box and pivoted the xenon into the light surround. When the light and box are in place plug the power lead into the box and push and twist the box in.
The other method is the put the xenon into the surround and balence it in there. Then get the box slide that down the gap, then (you'll need small fingers) twist the light into the box as said above avoiding touching the Xenon light as the grease on your fingers will boil on the light and make it pop! Now plug the power lead into the Xenon box and push and twist as said above.
It is very fiddley however you don't need to take the bumper, arch liners, wheels etc. off and saves you lots of time...
Also OP the lights are around 20 odd pound on Ebay. When the lights arrived they were from silvervision who have a good reputation. Don't get them from halfords as they ask for 60,(47 with trade card) and they're not the right bulb either.