They have separate covers on the back of the headlight unit but you do need hands like an 8 year old girl haha. Its a squeeze but its possible.
Its easy to take the front bumper off obviously but its alot of extra work.
Luckily i have a 12 year old sister who got her hands in there without...
1 year warranty on them to so even if they are rubbish and last a few months you can just send them back and get new ones under warranty! Haha. 10 quid well spent, there actually really good to.
I got 6000K bulbs which are a nice diamond white and not too blue.
They worked a treat in my 2007 S3 8P which is the same shape as yours so should be fine.
Deffo worth trying bulbs first although im not to sure on the price of the ballasts. Pretty expensive i imagine lol. :)
Got a knock sound comming from back right corner of my car sometimes when i brake and accelerate.
Its just a single knock which is quite high pitched almost like a tick rather than a knock.